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L  iPARTWENT  OF  PtfYSIOLi 

CoLLEae  OF  Pmy^ciaws  Y«p  Suroi 

NEW  y^Y. 


THE  EFFECT  OF  ODOURS 

IRRITANT  VAPOURS,  AND  MENTAL  WORK 

UPON  THE  BLOOD  FLOW 


DISSERTATION 

Presented  to  the  Board  of  University  Studies  of  The  Johns  Hopkins  University 

for  the  Degree  of  Doctor  of  Philosophy 

BY 

T.  E.  SHIELDS 
1895 


BALTIMORE 

1896 


From 

THE  JOURNAL  OF  EXPERIMENTAL  MEDICLNE 
Vol.  I,  No.  i,  1896 


o 


LC 


THE  EFFECT  OF  ODOUKS,  lEKITANT  VAPOURS,  AND 
MENTAL  WORK   UPON   THE   BLOOD   FLOW.* 

Plates  I-VII. 

By   T.   E.   shields,  Ph.  D. 

{From  the  Physiological  Laboratory  of  the  Johns  Hopkins  University.) 

Introduction  and  Desoeiption  of  Appakatus. 

Attempts  have  been  made  from  time  to  time  to  determine  the 
efiects  produced  by  various  sensations  on  the  circulation  of  the 
blood.  In  1877  a  series  of  experiments  was  conducted  by  MM. 
Gouty  and  Charpentier,  under  the  direction  of  M.  Vulpian,f  in  the 
hope  of  obtaining  a  more  exact  determination  of  these  disturbances. 
They  used  curarized  dogs  with  artificial  respiration  and  recorded  the 
results  on  a  kymograph  in  the  usual  manner  by  means  of  a  mercury 
manometer  in  connection  with  an  artery.  On  stimulating  the  various 
organs  of  special  sense  they  obtained  cardio-vascular  reactions  simi- 
lar in  many  respects  to  those  usually  obtained  by  stimulating  sensory 
nerves,  but  ditfering  markedly  from  these  in  their  greater  variability 
in  both  form  and  intensity  under  the  same  stimuli. 

Both  pneumogastric  nerves  were  then  severed.  Sensory  stimula- 
tion continued  to  produce  its  usual  eifect  on  arterial  tension,  but 
ceased  to  produce  any  effect  on  the  heart.  This  convinced  them  of 
the  fact  that  the  heart  disturbances  and  vasomotor  changes  were 
mediated  by  distinct  mechanisms. 

The  cerebral  cortex  of  fresh  subjects  was  then  shut  out  by  pres- 
sure, by  injection,  and  by  light  doses  of  chloral  hydrate.  In  every 
case  stimulation  of  the  organs  of  sense  failed  to  produce  any  effect, 
either  on  the  heart  or  on  arterial  pressure,  while  the  direct  stimula- 

*  A  thesis  submitted  to  the  Johns  Hopkins  University  for  the  degree  of  Ph.  D. 
f  De  I'influence  des  excitations  des  organs  des  sens  sur  le  coeur  et  sur  les  vaisseaux 
(recherches  exp.  faites  dans  le  lab.  de  M.  Vulpian),  note  de  MM.  Couty  et  Charpentier,  pre- 
sentee par  M.  Vulpian.     Comptes  Eendus,  t.  Ixxxv,  No.  3,  p.  161. 
1 

CoPTRiGHT,  1S96,  Br  D    Appleton  and  Compakt. 


2       Efect  of  Odours,  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

tion  of  a  peripheral  nerve,  such  as  tlie  sciatic,  continued  to  produce 
its  usual  effect.  From  these  facts  they  concluded  that  the  cardio- 
vascular disturbances  accompanying  sensory  stimulation  are  not  due 
directly  to  sensation  itself,  but  to  a  contingent  cerebral  activity  which 
they  called  emotion. 

Experiments  of  this  nature,  however  valuable  in  themselves,  will 
hardly  be  regarded  as  sufficient  data  from  which  to  draw  conclusions 
as  to  the  nature  and  extent  of  the  cardio-vascular  changes  accom- 
panying sensations  in  man.  Even  if  it  be  granted  that  cerebral  ac- 
tivity is  the  immediate  cause  of  the  cardio-vascular  changes  in  both 
man  and  dog,  it  does  not  follow  that  these  changes  will  be  the  same 
in  the  two  cases. 

In  1880  Dogiel  *  attempted,  by  means  of  the  plethysmograph,  to 
study  the  effects  of  music  on  the  circulation  of  the  blood  in  man. 
The  apparatus  used  contained  so  many  sources  of  error  that  even 
the  meagre  results  obtained  can  scarcely  be  regarded  as  reliable.  It 
is  to  Mosso's  t  researches  that  we  are  chiefly  indebted  for  what  definite 
information  we  possess  concerning  the  correlation  of  cerebral  func- 
tion and  cardio-vascular  changes  in  man,  but  our  literature  on  the 
whole  subject  of  the  changes  produced  in  the  circulation  in  response 
to  various  sensations  is  still  very  meagre.  This  is  particularly  true 
of  olfactory  sensations.  The  present  research  was  undertaken  in 
the  hope  of  throwing  some  light  on  this  problem. 

The  form  of  plethysmograph  devised  by  Mosso  was  first  used, 
and  the  volume  changes  in  the  arm  recorded  on  a  drum  kymograph ; 
but  it  soon  became  evident  that  several  sources  of  error  would  have 
to  be  eliminated  before  accurate  measurements  could  be  obtained. 
The  possibility  of  moving  the  arm  into  or  out  of  the  cylinder  during 
the  experiment  must  be  removed.  It  is  not  sufficient  to  request  the 
subject  to  sit  quietly,  nor  even  to  support  his  head  and  arm,  as  Dogiel  % 
'  did.  The  voluntary  effort  required  to  sit  immovable  is  itself  a  dis- 
turbing factor  in  the  circulation  of  the  blood.     Besides,  it  is  impos- 

*  Archivfur  Anat.  und  Physiol,  Physiol  Abthlg.,  1880.  S.  420  ff. 

f  Kreislauf  des  Blutes  im  menschlichen  Gehiru.     Von  A.  Mosso,  Leipzig,  1881. 

t  Op.  cit.,  pp.  419  et  429. 


T.  E.  Shields  3 

sible  to  prevent  movement  of  the  arm  for  any  considerable  time, 
since  normal  respiration  moves  the  arm.  Mosso's  *  plan  of  suspend- 
ing the  cylinder  from  the  ceiling  and  allowing  itjto  follow  the  move- 
ment of  the  arm  is  much  better,  but  even  here  the  inertia  of  the 
cylinder  filled  with  water  offers  sufficient  resistance  to  the  movements 
of  the  arm  to  produce  quite  a  perceptible  error.  I  think  it  probable 
that  the  respiratory  waves  f  often  obtained  by  the  plethysmograph 
are  due  in  greater  measure  to  this  movement  of  the  arm  than  to  the 
changes  in  its  volume  of  blood.  During  the  early  part  of  the  pres- 
ent research  I  frequently  obtained  marked  respiratory  waves,  but  in 
every  case  I  was  able  to  trace  them  to  this  movement  of  the  arm, 
and  when  the  movement  was  prevented  the  respiratory  waves  were 
very  much  diminished  if  not  entirely  suppressed. 

A  second  source  of  error  lies  in  the  fact  that  every  increase  of 
pressure  in  the  cylinder  tends  to  force  the  arm  out  of  it,  and  every 
diminution  of  pressure  exerts  an  opposite  influence.  The  play  of 
these  opposing  forces  is  felt  very  distinctly  on  the  inclosed  arm  dur- 
ing each  pulse  beat,  and  when  the  resulting  movement  of  the  arm  is 
prevented  the  record  of  the  pulse  wave  is  very  much  amplified. 
This  source  of  error  is  still  more  marked  in  sudden  large  vasomotor 
changes,  nor  can  it  be  eliminated  by  making  the  rubber  sleeve  so 
tight  that  it  will  not  slip  on  the  arm  ;  for  apart  from  the  two  obvious 
objections  to  this  mode  of  procedure— that  the  arm  should  be  oiled  :j: 
to  prevent  it  from  absorbing  water,  and  that  a  tight  sleeve  interferes 
with  normal  circulation— the  elastic  sleeve  itself  lengthens  and  short- 
ens in  response  to  changing  pressure  in  the  cylinder. 

There  is  still  another  source  of  error  connected  with  this  mode  of 
closing  the  cylinder  which  remains  even  after  all  movements  of  the 
arm  into  or  out  of  the  cylinder  have  been  prevented.  If  the  arm 
does  not  tit  the  mouth  of  the  cylinder  snugly  the  portion  of  the  elas- 
tic sleeve  between  the  arm  and  the  cylinder  will  yield  to  each  change 
of  pressure  in  the  cylinder.  The  panting  of  this  membrane  in  Te- 
sponse  to  the  pulse  may  be  seen  by  the  unaided  eye.     If  the  mouth 

Op.  cit.,  p.  44.  X  The  oil,  of  course,  increases  very  much  the  tendency  to  slip 

•f  Dogiel,  op.  cit,  p.  130. 


4      Lfect  of  Odours,  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

of  tlie  cylinder  be  large  enough  to  allow  the  elbow  to  enter,  it  will 
usually  be  found  much  too  large  to  fit  the  upper  arm.  This  was 
very  conspicuously  the  ease  in  the  cylinder  used  by  Dogiel  *  If  the 
cylinder  terminates  over  the  large  muscles  of  the  forearm,  as  it  does 
in  Mo^so's  arrangement,  it  can  be  made  to  fit  the  arm  snugly,  but 
another  source  of  error  appears.  Every  movement  of  the  inclosed 
fingers  withdraws  muscle  from  the  cylinder  or  introduces  muscle 
into  it. 


/////////////y//y/////////^^^^^ 


y//////////////////y///y//yy/y///^///y/yyyyy''yyy/y//////////M. 


Fig.  1. S,  rubber  sleeve ;  R,  ring  cemented  into  end  of  rubber  sleeve ;  A,  arm  ring ;  G, 

shoulder  in  same  ;  II,  bevelled  face  of  arm  ring  supporting  rubber  sleeve ;  C,  D,  rings  mak- 
ing arm  holder  rigid  to  cylinder;  X  N',  rods  connecting  the  rings  C  and  D;  W,  wristlet ; 
B,  band  for  same ;  M,  e,  I,  smaller  openings  in  arm  cylinder  ;  /t,  thermometer ;  t,  stopcock ; 
M  M',  metal  rods,  making  wristlet  rigid  to  arm  rmg. 

Fig.  1  is  a  sketch  of  a  device  for  removing  these  sources  of  error 
The  same  is  shown  in  Plate  II.     The  lettering  is  the  same  in  both. 

One  end  of  a  suitable-sized  rul)ber  sleeve,  S,  is  drawn  over  the 
arm  cylinder  and  fastened  in  position  by  a  ligature.  A  metal  ring, 
R,  large  enough  to  pass  readily  over  the  flange  is  cemented  into  the 
other  end  of  the  sleeve.  By  the  aid  of  this  ring  the  sleeve  is  easily 
doubled  back  over  the  flange  of  the  cylinder,  where  it  remains  until 
the  arm  has  been  put  into  position  in  the  cylinder.  A  hard-rubber 
wristlet,  provided  with  a  hinge  and  clasp,  tits  round  the  wrist.  A 
soft  band,  B,  passes  from  one  side  of  this  wristlet  between  the  thumb 
and  index  finger  and  is  buckled  to  the  other  side  of  the  wristlet  as 
tightly  as  comfort  will  permit.  A  second  hard-rubber  ring,  A,  pro- 
vided witli  hinge  and  clasp,  fits  the  arm  above  the  elbow.  This  ring 
is  rigidly  connected  with  the  wristlet  by  two  metal  rode,  M,  M'.     A 


*  Loc.  ci\ 


T.  E.  Shields  5 

shoulder,  G,  is  cut  into  one  face  of  this  ring  so  as  to  make  it  fit  into 
and  against  the  mouth  of  the  cylinder.  The  face,  H,  of  the  ring  is 
shaped  so  as  to  keep  the  rubber  sleeve  taut  down  to  the  point  where 
it  meets  the  arm.  "When  the  arm  has  been  introduced  into  the  cylin- 
der and  the  arm  ring  fitted  info  its  place,  the  rubber  sleeve  is  drawn 
down  over  it.  Two  hard-rubber  rings,  C  and  D,  rigidly  connected 
by  two  metal  rods,  N,  N',  and  provided  with  hinges  and  clasps,  are 
then  fastened  outside  the  rubber  sleeve.  One  of  these  rings,  C,  rests 
against  the  flange  of  the  cylinder;  the  other,  D,  fits  tightly  against 
the  outer  surface  of  the  arm  ring. 

This  arm  holder  reduces  toa  minimum,  if  it  does  not  entirely  re- 
move, the  sources  of  error  discussed  above.  All  movements  of  the 
elastic  sleeve  are  rendered  impossible.  The  arm  holder  is  made  ab- 
solutely rigid  to  the  cylinder.  The  wristlet,  with  its  tight  band  be- 
tween thumb  and  index  finger,  prevents  the  arm  from  moving  in 
the  holder.  As  the  inclosed  arm  can  not  bend,  no  muscle  can  be 
withdrawn  from  the  cylinder  or  introduced  into  it. 

The  arm  was  now  found  to  change  in  volume  about  one  cubic  cen- 
timetre at  each  pulse  beat.  This  introduced  a  new  difficulty  in  the 
recording  apparatus.  It  will  be  remembered  that  in  lilosso's^  ple- 
thysmograph  the  volume  changes  were  recorded  by  means  of  a  test 
tube  suspended  in  a  beaker  of  water  or  some  liquid  of  suitable  spe- 
cific gravity.  The  test  tube  was  counterpoised  by  a  weight  carrying 
the  recording  needle  and  connected  with  the  test  tube  by  two  threads 
passing  over  a  pulley.  However  well  this  arrangement  may  serve 
for  recording  slow  changes,  its  inadequacy  for  recording  such 
changes  as  we  are  here  dealing  with  is  evident.  The  introduction 
and  withdrawal  from  the  test  tube  of  a  cubic  centimetre  of  water  fifty 
to  one  hundred  times  a  minute  sets  up  considerable  agitation  in  the 
water  in  the  beaker,  where  every  motion  is  a  source  of  erroi*.  Be- 
sides, the  system  has  a  period  of  its  own  which  sometimes  neutral- 
ises the  pulse  effects  and  at  other  times  combines  with  them  to  pro- 
duce greatly  exaggerated  excursions  of  the  test  tube,  as  happens  in 

*  MM.  A.  Mosso  et  P.  Pellacani.     Sur  les  fonctions  de  la  vessie.     Archives  italiennes 
de  biologie,  vol.  i,  p.  08. 


6      Effect  of  Odours^  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

the  production  of  tone  beats.  The  great  inertia  of  the  system  also 
prevents  it  from  recording  accurately  such  rapid  changes  in  volume. 

The  method  adopted  by  Bowditch  *  of  suspending  the  test  tube 
from  a  spiral  spring  is  more  convenient.  This  removes  the  error 
which,  in  Mosso's  plan,  arises  from  the  motion  of  the  water  in  the 
beaker.  It  also  materially  lessens  the  inertia  of  the  system.  But 
the  great  inertia  still  remaining,  and  especially  the  periodicity 
of  the  spring,  compelled  me  to  seek  some  other  method  of  record- 
ing. I  had  recourse  to  a  water  manometer  of  large  bore  con- 
nected with  the  cylinder  by  a  wide,  indistensible  tube.  A  light  and 
buoyant  float  f  was  used  to  carry  the  recording  needle.  This  sys- 
tem, being  rigid,  and  having  no  period  of  its  own  except  that  due 
to  the  float,  gave  a  fairly  accurate  j'ecord  of  the  changes  occurring 
in  the  volume  of  the  arm;  but  it  introduced  a  new  source  of  error 
which  compelled  me  to  abandon  its  use.  The  level  of  the  water  in 
the  manometer  tube  determines  the  pressure  which  the  water  in  the 
cylinder  exerts  on  the  arm.  At  the  beginning  of  the  experiment 
the  manometer  may  be  set  so  as  to  exert  the  proper  pressure.  But 
in  the  course  of  the  experiment  every  change  in  the  volume  of  the 
arm  will  cause  a  change  of  pressure  on  its  surface.  The  arm  some- 
times changes  twenty  or  thirty  cubic  centimetres  in  volume  in  a 
few  seconds.  This,  of  course,  causes  a  corresponding  change  in  the 
level  of  the  water  in  the  manometer  tube,  wliich  in  turn  alters  very 
considerably  the  pressure  on  the  arm ;  nor  can  this  factor  be  neg- 
lected. I  found  that  the  change  of  pressure  due  to  an  alteration  of 
a  few  centimetres  in  the  level  of  the  water  in  the  manometer  caused 
a  very  large  change  in  the  volume  of  blood  in  the  arm.  That  is 
what  we  would  expect  from  the  low  blood  pressure  in  the  capillaries 
and  veins. 

Lehmann  ;}:  gives  the  following  account  of  the  apparatus  used  by 
him  in  investigating  the  effects   of   sensory  stimulation.     I  quote 

*  Proceedings  of  the  American  Academy,  May  14,  1879. 

\  Howell  and  Warfield.  Studies  from  Biological  Laboratory,  Johns  Hopkins  Umversiiy, 
vol.  ii,  p.  235. 

\  Die  Hauptgesetze  des  menschlichen  Gefiihlsleben.  Von  Dr.  Alfr.  Lehmann,  Leipzig, 
1892. 


T.  E.  Shields  '  Y 

his  description  in  full,  as  I  shall  have  occasion  to  refer  to  the  results 
obtained  later  on. 

"  Wir  haben  nun  die  Aufgabe  auf  die  Bestimmung  der  Atembe- 
wegungen,  des  Herzschlages  und  des  Yoluraens  eines  einzelnen 
Gliedmasses,  z.  B.  eines  Armes,  reduciert.  Die  erste  Bestimmung 
ist  mittels  des  Pneumographen  leicht  aiiszufiihren,  wahrend  die 
beiden  letzten  sich  mittels  Mosso's  Plethysmographen  zusammen 
ausfiihren  lassen.  Dieser  besteht  aus  einem  am  einen  Ende  ge- 
schlossenen  Eohr,  das  eben  weit  genug  ist,  den  Arm  zu  umschliessen, 
der  dnrch  einen  Gummiarmel  wasserdicht  mit  dem  Rohr  verbunden 
wird.  Durch  ein  Seitenrohr  wird  das  ganze  Kohr,  nachdem  der 
Arm  in  die  rechte  Stellung  gebracht  ist,  mit  Wasser  gefiillt,  und 
hierauf  wird  das  Seitenrohr  durch  einen  Gummischlauch  mit  einem 
Mareyschen  Schreibapparat  {tambour  enregisteur)  in  Yerbindung 
gebracht.  Jede  Yeranderung  des  Armvolumens  bewirkt  eine 
Hebuno;  oder  Senhuno;  des  Wassers,  durch  welche  die  Luft  im 
Schlauch  und  im  Schreibapparat  beeinflusst  wird,  und  die  Bewegnng 
wird  dann  vom  Stift  des  Schreibapparats  auf  eine  rotierende  Walze 
(das  Kymographion)  gezeichnet." 

Lehmann's  apparatus  seems  to  be  a  Mosso  hydros phygmograph  * 
in  which  the  bottle  tor  keeping  the  pressure  constant  has  been 
omitted  so  as  to  compel  the  tambour  to  register  both  pulse  and  vaso- 
motor eifects.  In  both  these  forms  of  apparatus  the  pressure  on  the 
arm  is  too  high.  The  air  cushion  is  at  the  top  of  the  cylinder. 
The  whole  arm  is  consequently  under  a  positive  pressure  of  some 
centimetres  of  water.  The  under  surface  of  the  arm  can  scarcely  be 
under  a  pressure  of  less  than  twelve  centimetres.  If  the  cylinder  be 
large  enough  to  extend  above  the  elbow,  as  it  should  do  in  order  to 
escape  a  source  of  error  mentioned  above,  this  pressure  is  likely  to 
be  still  higher. 

The  form  used  by  Lehmann  introduces  another  grave  source  of 
error.  In  dispensing  with  the  pressure  bottle,  the  tambour  and 
cylinder  are  rendered  a  closed  system  in  which  every  change  of 
volume  in  the  arm  alters  the  pressure  on  its  surface.     If,  as  some- 

*  Diagnostik  des  Pulses.     Von  Dr.  A.  Mosso,  Leipzig,  18Y9. 


8      Effect  of  Odours^  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

times  happens,  twenty-five  or  thirty  cubic  centimetres  of  blood  be 
added  to  the  volume  of  the  arm,  the  distention  of  the  membrane  of 
the  tambour  necessary  to  make  room  for  this  increased  volume  of 
blood  would  exert  a  considerable  pressure  on  the  arm. 

Besides  the  sources  of  error  enumerated  in  connection  with  each 
of  the  forms  of  apparatus  discussed  above,  there  is  a  defect  common 
to  them  all.  We  have  seen  that  the  changes  in  volume  of  blood  in 
the  arm  are  due  to  at  least  two  distinct  sources — changes  in  the 
heart's  action  and  changes  in  the  calibre  of  peripheral  vessels.  It  is 
therefore  highly  desirable  that  the  record  of  these  two  effects  be 
kept  as  distinct  as  possible.  Whenever,  as  is  the  case  with  each  of 
these  forms  of  apparatus,  the  same  writing  point  is  made  to  record 
the  pulse  and  the  gross  volume  changes,  these  effects  partially  mask 
each  other  and  do  not  stand  out  as  distinctly  as  they  should.  This 
is  illustrated  very  well  by  many  of  the  curves  published  in  Leh- 
mann's  work.  I  have  a  large  number  of  similar  curves  in  my  own 
possession  which  I  obtained  by  the  use  of  these  forms  of  apparatus. 

From  what  has  been  said,  it  is  evident  that  an  efficient  apparatus 
for  recording  the  volume  changes  in  the  arm  must  at  least  meet  the 
following  three  requirements:  First,  the  pulse  and  vasomotor  effects 
should  be  recorded  separately  ;  second,  the  apparatus  for  recording 
the  rapid  and  rhythmic  changes  of  volume  due  to  the  pulse  should 
have  very  little  inertia  and  no  periodicity;  tliird,  the  pressure  ex- 
erted on  the  arm  should  be  as  nearly  normal  as  possible,  and  must 
remain  constant  during  all  changes  of  volume  which  may  occur  in 
the  arm.  These  requirements  are  met  fairly  well  by  the  following 
arrangement : 

A  long  metal  tube.  A'  (Plate  I),  is  slipped  over  an  upright,  U, 
to  which  it  is  fastened  by  a  clamp,  C.  The  top  of  the  upright  is 
held  in  position  by  two  metal  rods,  M,  M',  which  make  it  rigid  to 
the  wooden  screen  interposed  between  the  subject  and  the  kymo- 
graph. A  short  metal  tube,  B,  is  supported  in  a  vertical  position  by 
two  clamps,  D,  D',  which  make  it  rigid  to  the  upper  end  of  tube  A. 
One  end  of  a  long  close  spiral,  S,  of  l^o.  5  piano  wire  is  slipped  over 
the  lower  end  of  the  tube,  B,  and  fastened  to  it  by  a  clamp,  E.    Two 


T.  E.  Shields  9 

wires,  F,  F,  pass  down  from  the  free  end  of  the  spiral,  and  are  fas- 
tened by  two  small  binding  screws  to  a  light  hard-rubber  ring,  K, 
one  inch  in  diameter.  By  suitable  cork  collars,  test  tubes  of  various 
sizes  may  be  suspended  from  this  ring.  The  slipping  of  the  wire 
under  clamp  E  permits  the  length  of  spiral  to  be  so  adjusted  that 
the  level  of  the  water  in  the  suspended  test  tube  will  remain  constant 
while  the  quantity  of  water  in  the  test  tube  varies.  One  arm  of  a 
long  glass  siphon,  G,  is  passed  down  through  tube  B,  thence 
through  the  centre  of  the  spiral  S,  and  dipped  a  few  millimetres 
beneath  the  surface  of  the  water  in  the  test  tube  T.  The  siphon  is 
centred  and  held  in  position  by  six.  set  screws  passing  through  tube 
B.  An  indistensible  tube,  H  I,  connects  the  other  end  of  the  siphon 
with  the  arm  cylinder.  The  four-way  J  interposed  in  this  tube  will 
be  described  later. 

This  is  essentially  the  same  as  the  apparatus  described  by  Bow- 
ditch,  to  which  reference  has  already  been  made.  Its  inertia  unfits 
it  for  recording  the  changes  in  volume  due  to  the  pulse.  Its  perio- 
dicity combining  with  the  rhythmic  pulse  at  times  neutralizes  the 
pulse  effects,  and  at  other  times  combines  with  them  to  produce 
greatly  exaggerated  excursions  of  the  test  tube.  The  pulse  and  vaso- 
motor effects  also  partially  mask  each  other.  The  pulse  effects  are 
the  disturbing  factor  in  each  case ;  if  they  be  removed  from  the 
test  tube  and  recorded  separately,  the  instrument  is  well  adapted  for 
registering  the  vasomotor  effects. 

By  the  following  device  this  separation  of  the  pulse  record  from 
the  vasomotor  record  may  be  attained,  the  pulse  wave  being  recorded 
by  a  tambour  the  tension  of  which  remains  practically  constant  ex- 
cept for  the  variation  with  each  pulse  wave  and  the  vasomotor 
changes  being  recorded  by  the  test  tube  and  spiral  spring  already 
described,  which  are  so  arranged  that  only  the  slow  vasomotor 
changes  in  the  volume  of  the  arm  cause  any  perceptible  movement 
of  the  system,  the  quicker  changes  due  to  the  heart  heat  disappear- 
ing from  this  record.  A  wide  glass  piston  tube  (K,  Fig.  2  and  Plate 
I ;  P,  Plate  II)  is  supported  in  a  vertical  position  beside  the  arm 
cylinder,  with  the  bottom  of  which  it  communicates  freely.     The 


10     Efect  of  Odours,  Irritant  Vapours,  etc.,  xipon  the  Blood  Flow 


TO  TAMBOUR 


Fig.  2. — K,  piston  tube ;  *  P,  piston  ;  N,  piston  rod ;  Q,  milled  nut  for  adjusting  level 
of  piston  ;  Q',  milled  nut  for  adjusting  indicator ;  (/,  metal  cap  of  piston  tube  ;  W,  washer, 
giving  support  to  nut  Q  in  lowering  piston ;  0,  0',  rods  supporting  washer ;  v,  tube  connect- 
ing with  tambour ;  Y,  T-way  ;  A,  B,  stopcocks  on  same ;  X,  tambour ;  e,  tambour  lever  carry- 
ing horizontal  pivot ;  k,  horizontal  pivot ;  /t,  vertical  pivot. 

*  The  vertical  piston  tube  allows  the  pressure  of  the  water  on  the  arm  to  be  regulated 
at  pleasure.  The  piston  in  this  tube  serves  to  keep  the  volume  of  the  air  between  the 
water  and  the  tambour  constant. 


T.  E.  Shields  11 

upper  end  of  the  tube  is  incased  in  a  metal  cap,  L  (Fig.  2),  which  is 
perforated  to  allow  free  play  to  the  hollow  piston  rod,  N,  and  free 
communication  between  the  air  in  the  upper  end  of  the  piston  tube 
and  the  atmosphere.  From  this  cap  two  metal  rods,  O,  O',  parallel 
with  the  piston  tube  extend  upward  about  one  inch  and  hold  in 
place  a  washer,  W,  which  encircles  the  piston  rod.  Between  the 
washer  and  the  cap  a  milled  nut,  Q,  fits  on  the  piston  rod,  whi:h  is 
threaded  from  end  to  end.  The  piston  rod,  'N,  is  a  metal  tube  one 
eighth  of  an  inch  in  diameter,  which  extends  through  an  otherwise 
air-tight  piston,  P,  in  the  piston  tube.  A  small  indistensible  tube,  Y, 
connects  the  upper  end  of  the  piston  rod  with  a  Marey  tambour,  X. 
A  T-waj,  Y,  provided  with  two  stopcocks,  A,  B,  interposed  in  the 
course  of  this  tube,  permits  connection  between  the  air  cushion  be- 
low the  piston  and  the  tambour  or  the  atmosphere  to  be  made  or 
broken  as  desired.  A  milled  nut,  Q',  fitting  the  piston  rod  above  the 
washer,  carries  an  indicator,  which  passes  down  through  a  perfora- 
tion in  the  washer,  thence  through  a  perforation  in  the  flange  of  the 
metal  cap,  and  terminates  below  the  level  of  the  piston.  The  dis- 
tance between  the  point  of  the  indicator  and  the  lower  surface  of 
the  piston  measures  the  vertical  height  of  the  air  cushion  in  the  pis- 
ton tube.  It  can  be  set  at  any  desired  distance  by  means  of  the  nut 
Q'.  Since  the  indicator  is  carried  by  the  piston  rod,  the  distance 
between  its  point  and  the  piston  remains  constant  whatever  altera- 
tions may  be  made  in  the  level  of  the  piston.  The  level  of  the  water 
in  the  piston  tube  when  the  air  cushion  is  in  communication  with 
the  atmosphere  indicates  the  pressure  exerted  by  the  water  on  the 
surface  of  the  inclosed  arm.  For  convenience  in  registering  this 
pressure  a  centimetre  scale  is  affixed  to  the  side  of  the  piston  tube. 

The  arm  cylinder  is  of  the  usual  form  (see  Plate  II).  A  flexible 
metal  band,  Y,  encircles  the  cylinder  near  one  end  and  is  closed  over 
the  upper  surface  of  the  cylinder  by  a  nut  and  bolt.  To  this  bolt 
are  also  fastened  two  chains  which  pass  round  the  cylinder  in  oppo- 
site directions,  and  thence  through  a  ring,  d,  which  is  suspended  some 
distance  above  the  cylinder.  The  chains  are  doubled  back  and 
hooked  on  themselves  at  desired  lengths.     The  other  end   of  the 


12     Effect  of  Odovrs^  Irritant  Vapours^  etc.,  upon  the  Blood  Elow 

cylinder  is  suspended  in  a  similar  manner  from  the  same  rin<r. 
Tiiese  chains  serve  to  keep  the  cyh'nder  in  a  horizontal  position  and 
to  prevent  it  from  rotating.  A  litth  chain,  from  which  the  ring  d 
is  suspended,  passes  through  a  pulley  fastened  to  the  ceiling,  thence 
down  to  a  ratchet  which  is  supported  at  convenient  height.  By 
turning  this  ratchet  the  cylinder  is  raised  or  lowered  to  suit  the  com- 
fort of  the  subject. 

Besides  the  opening  through  which  the  arm  is  introduced,  the 
cylinder  is  provided  with  three  other  smaller  orifices.  Through  one 
of  these,  Z,  situated  on  the  end  of  the  cylinder,  communication  is 
made  with  the  suspended  test  tube  used  to  record  the  vasomotor 
changes.  A  second  orifice,  e,  provided  with  a  tight-fitting  rubber 
stopper  through  which  two  perforations  have  been  made,  is  located 
on  the  upper  surface  of  the  cylinder.  A  glass  stopcock,  ^,  is  fitted 
into  one  of  these  perforations.  The  bulb  of  a  thermometer,  h,  is  in- 
troduced through  the  other.  On  the  under  surface  of  the  cylinder 
is  a  third  orifice,  M,  into  which  is  fitted  one  branch  of  a  large  T-way. 
A  second  branch  of  this  T-way  communicates  with  the  lower  end  of 
the  piston  tube.  The  third  branch  is  connected  with  the  tube  k  for 
filling  and  emptying  the  cylinder. 

1  have  found  the  following  method  convenient  for  filling  and 
emptying  the  cylinder,  for  regulating  the  temperature  and  pressure 
of  the  water,  and  for  adjusting  the  instrument: 

The  piston  is  raised  or  lowered  by  turning  the  milled  nut  Q  until 
the  point  of  the  indicator  stands  at  the  level  to  which  it  is  desired  to 
bring  the  water  in  the  piston  tube.  Two  supply  jars,  P,  Q  (Plate  I) 
— one  filled  with  hot  water,  the  other  with  cold  water — are  placed 
on  a  shelf  attached  to  the  screen  above  the  level  of  the  test-tube 
siphon,  G.  Two  siphons  connect  these  jars  with  two  branches  of  a 
large  three-way  stopcock,  w,  which  permits  the  hot  and  cold  water  to 
be  mixed  in  the  desired  proportions.  The  bulb  of  a  thermometer 
for  indicating  the  temperature  of  the  water  is  placed  in  the  tube, 
which  conducts  the  water  from  the  three-way  w  to  one  branch  of  a 
second  large  three-way,  2.  A  tube  connects  a  second  branch  of  this 
three-way  with  the  arm  cylinder ;  another  tube  leads  from  its  third 


T.  E.  Shields  13 

branch  to  the  sink.  This  three-way  allows  the  water  to  pass  from 
the  three-way  w  to  the  cylinder,  or  from  the  cylinder  to  the  sink,  or 
from  a  hydrant  tap  to  the  supply  jars,  as  may  be  desired. 

The  four-way  J,  each  branch  of  which  is  provided  with  a  stop- 
cock, is  made  rigid  to  the  tube  A,  at  a  level  somewhat  lower  than 
that  of  the  arm  cylinder.  One  of  these  stopcocks  (I)  opens  into  the 
test-tube  siphon  ;  a  second  (2)  communicates  with  the  arm  cylinder; 
a  third  (3)  is  connected  by  a  siphon  with  one  of  the  supply  jars;  a 
tube  from  the  fourth  (4)  leads  to  the  sink. 

When  the  subject's  arm  has  been  coated  with  vaseline  and  placed 
in  the  arm  cylinder,  as  directed  above,  stopcock  t,  on  the  upper  sur- 
face of  the  arm  cylinder,  is  opened  to  allow  the  air  to  escape.  Stop- 
cocks A  and  B  (Plate  I  and  also  Fig.  2)  are  closed  to  cut  off  connec- 
tion between  the  air  cushion  of  the  piston  tube  and  the  atmosphere 
and  tambour.  Stopcocks  1  and  2,  on  the  four-way,  are  opened,  and 
stopcocks  3  and  4  closed.  Three-way  stopcocks  w  and  s  are  ad- 
justed so  as  to  allow  water  of  the  proper  temperature  to  enter  the 
arm  cylinder.  When  the  cylinder  is  within  a  few  cubic  centimetres 
of  being  full  the  supply  of  water  from  this  source  is  shut  off,  and  a 
strong  clamp  placed  on  the  supply  tube  at  the  point  where  it  meets 
the  cylinder,  to  prevent  any  possible  error  that  might  otherwise 
arise  from  leakage  or  from  distention  of  the  supply  tube.  Stopcock 
3,  on  the  four-way,  is  now  opened  and  water  allowed  to  flow  into  the 
cylinder  until  it  is  filled,  when  the  stopcock  at  the  top  of  the  cylin- 
der {t,  Plate  II)  is  closed  to  prevent  air  from  re-entering  the  arm 
cylinder.  Stopcock  2,  on  the  four-way,  is  closed  at  the  same  moment 
to  prevent  increase  of  pressure  on  the  arm  while  the  test-tube  siphon 
is  being  filled.  When  the  test  tube  is  partially  filled,  stopcock  3  is 
closed  and  stopcock  2  opened.  If  the  test  tube  is  too  full  at  any 
time,  water  may  be  drawn  off"  by  opening  stopcock  4.  Stopcock  B 
is  now  opened,  thus  establishing  free  communication  between  the 
air  cushion  and  the  atmosphere.  The  water  in  the  piston  tube  will 
now  rise  to  the  same  level  as  that  in  the  test  tube.  Tube  A',  carry- 
ing the  test  tube  and  its  appurtenances,  is  slowly  raised  or  lowered 
on  the  upright  until  the  level  of  the  water  in  the  piston  tube  reaches 


14    Effect  of  Odours^  Irritant  Vapours^  etc.^  upon  the  Blood  Flow 

the  point  of  the  indicator.  Stopcock  B  is  tlien  closed  and  stopcock 
A  opened,  thus  putting  the  air  cushion  in  communication  with  the 
tambour.  The  lever  of"  the  tambour  will  now  give  a  magnified  rec- 
ord of  the  changes  in  the  level  of  the  water  in  the  piston  tube.  If 
the  resistance  offered  by  the  long  narrow  tube,  H  I,  to  the  rapid  pas- 
sage of  water  between  the  test  tube  and  the  arm  cj'linder  is  not  suf- 
ficient to  prevent  the  changes  of  volume  due  to  the  pulse  from  mov- 
ing the  test  tube,  this  resistance  is  increased  to  the  desired  extent  by 
partially  closing  stopcocks  1  and  2  on  the  four-way.  The  small  and 
rapid  changes  of  volume  due  to  the  pulse  are  consequently  recorded 
by  the  tambour  alone,  while  the  slower  and  larger  volume  changes, 
freed  from  pulse  waves,  are  recorded  by  the  motions  of  the  test  tube, 
on  the  same  principle  that  the  height  of  the  tide  is  recorded  by  the 
level  of  the  water  in  the  vertical  pipe  of  the  tide  gauge,  while  the 
separate  waves  are  prevented  from  influencing  this  level  by  the 
resistance  which  the  holes  in  the  bottom  of  the  pipe  offer  to  the  rapid 
passage  of  water. 

This  form  of  apparatus  reduces  very  much  the  sources  of  error 
discussed  above.  The  suspended  test  tube  is  entirely  freed  from  the 
error  due  to  the  periodicity  of  the  spring.  The  inertia  of  this  system 
ceases  to  be  a  grave  source  of  error  owing  to  the  slowness  of  the 
motions  which  it  is  now  required  to  execute.  The  tambour,  relieved 
for  the  most  part  from  the  disturbing  factor  of  large  volume  changes, 
gives  a  fairly  accurate  record  of  the  pulse  waves.  The  chief  source 
of  error  remaining  is  the  pressure  exerted  by  the  water  on  the  arm. 
It  is,  of  course,  impossible  to  have  an  arm  immersed  in  water  under 
perfectly  normal  pressure.  I  have  found  the  conditions  to  be  most 
favourable  when  the  level  of  the  water  in  the  piston  tube  is  that  of 
the  middle  of  the  arm,  the  lower  half  of  the  arm  being  then  under  a 
positive  pressure  of  a  few  centimetres  of  water,  and  the  upper  half 
under  a  like  amount  of  negative  pressure. 

Each  pulse  wave  is  accompanied  by  a  slight  change  of  pressure 
on  the  arm,  due  to  the  resistance  which  the  water  in  the  cylinder 
offers  to  the  entrance  of  the  wave.  This  resistance  is  made  up  of 
several  factors:    First,  the  inertia  of  the  volume  of  water  to  be 


T.  E.  Shields  15 

moved ;  second,  the  force  of  gravity  to  be  overcome  in  slightly- 
raising  the  level  of  the  water  in  the  piston  tube  ;  and  third,  the  re- 
sistance offered  by  the  air  cushion  in  the  piston  tube  to  change  in  the 
level  of  the  water  in  the  tube.  The  last-named  resistance  is  due  to  the 
tension  of  the  membrane  of  the  tambour  and  to  the  inertia  and  friction 
of  the  recording  lever.  These  sources  of  error  are  quite  small,  but 
they  still  exist,  and  should  be  taken  into  account  in  calculating  results. 
The  resistance  offered  by  the  air  cushion  has  been  rendered  very 
slight  by  reduction  in  the  weight  and  friction  of  the  recording  lever, 
and  by  the  delicacy  and  low  tension  of  the  tambour  membrane.  The 
inertia  of  the  mass  of  water  to  be  moved  may  be  reduced  somewhat 
by  so  changing  the  form  of  the  arm  cylinder  as  to  diminish  the  dis- 
tance between  the  surface  of  the  water  in  the  piston  tube  and  the 
point  where  the  expansion  of  the  inclosed  arm  first  occurs..  The 
wider  the  piston  tube,  the  less  the  change  in  the  level  of  the  water 
caused  by  the  pulse  wave ;  but  the  pulse  recorder  becomes  propor- 
tionally more  sensitive  to  vasomotor  changes.  When  there  is  a 
sudden  large  change  in  the  volume  of  the  arm,  the  vasomotor 
recorder  can  not  take  care  of  it  rapidly  enough.  There  is,  in  conse- 
quence, a  temporary  variation  in  the  level  of  the  water  in  the  piston 
tube,  which  interferes  somewhat  with  the  pulse  recorder  and  changes 
the  pressure  on  the  arm.  The  influence  of  this  disturbing  factor, 
which  I  have  not  yet  been  able  entirely  to  eliminate,  will  receive 
attention  when  we  come  to  discuss  the  results. 

In  the  early  part  of  the  investigation,  I  used  a  Ludwig  drum 
kymograph,  with  smoked  paper  for  recording  the  curves.  It  soon 
became  evident,  however,  that  this  plan  of  recording  presented 
another  grave  difiiculty. 

Spontaneous  changes,  or  at  least  changes  not  due  to  sensory  stim- 
ulation, were  continually  appearing  in  both  vasomotor  and  pulse 
curves.  It  was,  therefore,  necessary  to  have  a  continuous  record 
of  the  changes  going  on  in  the  arm  for  some  time  before  and  after 
stimulation,  in  order  to  be  able  to  differentiate  them  from  any  sen- 
sory reactions  that  might  appear.  This  is  impossible  with  the 
Ludwig  drum  kj-mograph,  for  if  it  be  made  to  travel  fast  enough  to 


16     Effect  of  Odours,  Irritant  Vapours,  etc.,  upon  tlie  Blood  Flow 

bring  out  the  pulse  curve,  the  paper  will  be  used  up  in  three  or  four 
minutes,  and  it  will  be  necessary  to  stop  and  put  on  fresh  paper. 
An  ink  record  on  a  continuous  band  of  paper  is  evidently  what  is 
needed.  The  chief  difficulty  in  obtaining  such  a  record  is  the 
resistance  to  be  overcome  in  moving  the  vasomotor  and  pulse  pens. 
I  was  unable  to  reduce  this  sufficiently  in  the  case  of  vertical  kymo- 
graphs for  continuous  paper,  and  accordingly  built  a  horizontal 
kymograph,  the  general  arrangement  of  which  is  shown  in  Plate  I. 
By  special  contrivances  for  suspending  and  moving  the  pens  the 
resistance  was  reduced  within  tlie  limits  of  that  offered  by  the  smoked 
paper. 

A  light  plate  of  aluminium  foil  is  cut  in  the  form  of  a  cross.  The 
two  ends  of  the  transverse  beam  widen  out  and  are  bent  so  as  to 
clasp  tightly  the  tube  of  a  glass  pen.  The  ends  of  the  other  beam  of 
the  cross  are  bent  into  hooks,  from  one  of  which  a  thread  passes 
over  a  pulley  adjusted  to  the  side  of  the  kymograph,  and  is  held 
taut  by  a  small  weight.  From  the  hook  on  the  other  end  of  the 
beam  a  thread  passes  under  a  pulley  adjusted  to  the  other  side  of  the 
kymograph,  and  thence  vertically  to  a  violin  key,  which  turns  in  a 
cork  holder  cemented  to  the  bottom  of  the  test  tube  used  for  record- 
ing the  vasomotor  changes.  This  key  is  turned  until  the  pen  rests 
over  the  centre  of  the  paper.  A  thread  fastened  to  the  bulb  of  the 
pen  passes  vertically  to  a  similar  violin  key,  wliich  is  supported  in 
proper  position.  The  tube  of  the  pen,  at  a  point  somewhat  beyond 
where  it  leaves  the  holder,  is  bent  downward  through  an  angle  of 
about  45°.  The  key  to  which  the  vertical  thread  supporting  the 
bulb  of  the  pen  is  fastened  is  turned  until  the  point  of  the  pen  just 
touches  the  paper.  The  pulleys  are  so  adjusted  that  the  upper  por- 
tion of  the  pen  will  be  about  horizontal.  The  thread  passing  be- 
tween the  pulleys  is  horizontal  also,  except  for  the  sag  in  the  middle, 
caused  by  the  weight  of  the  pen.  As  the  pen  moves  from  either 
pulley  toward  the  other  it  describes  a  curve,  due  to  the  sag  in  the 
horizontal  thread.  This  curvilinear  motion  is  neutralized  in  the 
point  of  the  pen  by  the  pendular  motion  of  the  bulb,  due  to  the 
thread  from  which  it  is  suspended,  the  factors  in  this  adjustment 


T.  E.  Shields  lY 

being  the  extent  of  the  sag,  the  length  of  the  pendular  thread,  and 
the  respective  distances  of  the  point  and  bulb  of  the  pen  from  the 
horizontal  thread.  The  extent  of  the  sag  is  controlled  by  the  size  of 
the  weight  on  the  end  of  the  thread.  The  length  of  the  pendular 
thread  is  regulated  bj  raising  or  lowering  the  key  holder  from  which 
it  is  suspended.  The  distance  of  the  ends  of  the  pen  from  the  hori- 
zontal thread  is  controlled  by  moving  the  pen  in  its  holder. 

The  friction  between  the  point  of  this  pen  and  the  paper  is  very 
small,  since  the  point  need  not  actually  touch  the  paper,  the  capil- 
lary attraction  between  the  paper  and  the  meniscus  being  sufficient 
to  cause  the  ink  to  flow  if  the  pen  be  properly  made.  But  even 
when  the  point  of  the  pen  actually  touches  the  paper,  it  does  so  very 
lightly.  If  the  point  of  the  pen  be  lifted  by  a  finger  until  the  sag 
leaves  the  horizontal  thread,  half  of  the  weight  of  the  tube  of  the 
pen  will  rest  on  the  finger.  If  the  finger  be  now  gradually  lowered, 
the  weight  on  it  will  be  found  progressively  to  diminish  and  finally 
to  disappear,  having  been  thus  shifted  to  the  horizontal  thread. 
This  gives  very  great  buoyancy  to  the  point  of  the  pen  and  reduces 
friction  to  a  minimum. 

The  pulleys  are  large  and  very  light,  and  are  pivoted  in  a  manner 
similar  to  the  balance  wheel  of  a  watch.  Their  friction  is  thus 
rendered  very  small.  The  inertia  due  to  the  pen,  its  aluminium 
holder,  and  the  light  weight  on  the  end  of  the  horizontal  thread,  is 
relatively  a  very  small  addition  to  that  of  the  test  tube  partially 
filled  with  water;  but  the  inertia  of  this  whole  system,  large  as  it  is, 
has  very  little  influence  on  the  accuracy  of  the  record,  owing  to  the 
slowness  of  the  motions  which  it  describes. 

The  tambour,  x  (Fig.  2  and  Plate  I),  of  the  pulse  recorder  is  sup- 
ported with  its  membrane  vertical.  The  motions  of  this  membrane 
are  communicated  to  one  end  of  a  light  aluminium  lever,  e,  which 
just  after  passing  through  a  pivot,  h,  whose  axis  is  vertical'  bends 
upward  at  a  right  angle,  and  after  running  in  this  direction  about 
one  inch  supports  a  second  pivot,  h,  whose  axis  is  horizontal  and 
perpendicular  to  the  long  axis  of  the  paper.  A  light  glass  pen,  I, 
with  a  long  tube  is  passed  through  this  pivot  and  fastened  to  it  when' 


18     Effect  of  Odours^  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

the  bulb  of  the  pen  is  directly  over  the  axis  of  the  first  pivot.  The 
motion  of  the  membrane  will  now  impart  a  magnified  horizontal 
movement  to  the  point  of  the  pen,  while  its  bulb,  being  in  the  axis 
of  the  pivot,  only  undergoes  a  very  slight  rotary  motion.  The  sec- 
ond pivot  allows  the  pen  to  njove  freely  in  a  vertical  plane.  Ink  is 
now  poured  into  the  bulb  of  the  pen  until  the  point  of  the  pen 
barely  rests  on  the  paper.     The  friction  here  is  very  slight. 

The  pens  for  the  pneumograph  (to  record  the  respiratory  move- 
ments), the  time  marker,  and  the  signal  marking  the  time  of  applica- 
tion of  the  stimulus,  are  pivoted  in  a  slightly  different  manner,  but 
one  which  involves  the  same  principle.  The  bulb  of  the  pen  with 
the  ink  which  it  contains  acts  in  each  case  as  a  counterpoise  to  the 
long  tube  of  the  pen,  thus  causing  the  point  to  rest  on  the  paper  as 
lightly  as  desired.  A  horizontal  movement  is  imparted  to  the  point 
of  the  pen  by  a  fork  of  the  tambour  lever  or  of  an  armature  of  an 
electro-magnet,  as  the  case  may  be.  For  this  purpose  the  pen  must 
be  free  to  move  round  two  axes,  one  vertical  and  the  other  hori- 
zontal. 

The  points  of  the  five  pens  are  adjusted  so  as  to  fall  in  a  line  per- 
pendicular to  the  long  axis  of  the  paper.  The  test  tube  used  in  the 
vasomotor  recorder  was  of  such  a  calibre  that  three  cubic  centimetres 
of  water  moved  it  one  centimetre.  The  paper  travelled  from  right  to 
left;  the  time  record  is  nearest  the  test  tube,  and  consequently  at  the 
bottom  of  the  paper.  Movement  of  vasomotor  or  pulse  pen  toward 
the  bottom  of  the  paper  represents  diminishing  volume  of  arm,  and 
conversely.  I  used  the  time  record  as  base  line  in  calculating  the 
volume  changes.  If  6?  represents  the  initial  distance  in  centimetres 
between  the  point  of  the  vasomotor  pen  and  the  base  line,  and  d'  its 
distance  in  any  subsequent  position,  then  (tZ'  —  oT)  X  3  =  F",  where  F"  is 
the  volume  change  in  cubic  centimetres.  If  at  any  time  during  the 
experiment  the  test  tube  is  becoming  overfilled,  stopcock  2,  Plate  I, 
on  the  four-way,  is  closed  and  stopcock  4  opened  until  the  desired 
amount  is  drained  off.  Stopcock  4  is  then  closed  and  stopcock  2 
opened,  and  the  fact  noted  on  the  paper.  The  point  of  the  pen,  of 
coarse,  records  the  volume  drawn  out,  which  must  be  added  in  cal-' 


T.  E.  Shields  19 

cnlating  subsequent  changes.  If  the  test  tube  is  in  danger  of  being 
emptied,  water  is  introduced  through  stopcock  3  in  a  similar  man- 
ner, and  the  amount  subtracted  in  all  subsequent  calculations. 
Specimens  of  the  curves  traced  by  this  instrument  may  be  seen  in 
Plate  in. 

Being  thus  enabled  to  obtain  what  I  believed  to  be  a  fairly  accu- 
rate record  of  the  changes  which  actually  occur  in  the  volume  of 
the  arm,  I  proceeded  to  study  the  influences  which  determine  these 
changes  in  the  hope  of  being  able  to  eliminate  some  of  them  and  to 
differentiate  the  changes  which  would  remain  from  any  odour  reac- 
tions I  might  obtain. 

I  first  determined  empirically  what  temperature  of  water  and 
what  pressure  on  the  arm  would  maintain  the  most  constant  volume 
of  blood  in  the  arm.  The  most  favourable  pressure,  as  has  already 
been  stated,  is  that  which  is  exerted  when  the  level  of  the  water  in 
the  piston  tube  was  about  that  of  the  middle  of  the  arm.  When  I 
used  pressure  lower  or  higher  than  this  the  arm  exhibited  a  tendency 
to  increase  or  diminish  in  volume.  The  proper  temperature  of  water 
I  found  to  be  between  30°  and  34°  C,  according  to  the  temperature 
of  the  room  and  of  the  arm  of  the  subject.  I  found  that  this  tem- 
perature kept  the  volume  of  the  arm  more  constant  than  any  other, 
and  I  found  also  that  the  temperature  of  the  water  in  the  cylinder 
remained  constant  throughout  the  experiment,  whereas,  if  the  tem- 
perature be  higher  at  the  beginning,  it  will  sink  during  the  experi- 
ment, and  conversely,  if  the  initial  temperature  be  lower. 

After  the  experiment  had  been  continued  for  about  half  an  hour, 
large  and  frequent  changes  of  volume  usually  occurred,  which  I  at- 
tributed to  the  discomfort  of  the  subject,  who  up  to  this  time  had 
been  seated  on  a  wooden  chair.  These  disturbing  factors  were  re- 
moved by  putting  the  subject  in  an  invalid  chair  which  could  be  ad- 
justed to  any  desired  position.  He  could  rest  here  comfortably,  with 
all  his  muscles  as  completely  relaxed  as  if  he  were  in  bed.  This  ren- 
dered the  volume  of  the  arm  much  more  constant.  But  the  most 
conspicuous  of  the  disturbing  factors  still  remained.  This  is  the 
mental  reaction.     Apparently,  every  thought  that  flits  across  the 


20     Effect  of  Odours^  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

subject's  mind  records  its  presence  b}"  a  change  of  volume  in  the 
arm.  Talking  in  the  room,  the  entrance  of  a  stranger,  the  striking 
of  a  clock,  or  a  noise  in  an  adjoining  room,  is  usually  accompanied 
by  a  change  of  volume  in  the  arm,  and  this  sometimes  even  when 
the  subject  is  asleep.  This  is  what  was  to  be  expected  from  the 
correlation  which  Mosso  has  shown  to  exist  between  cerebral  func- 
tion and  the  volume  of  the  arm.*  Nor  do  I  see  any  way  in  which 
this  disturbing  factor  can  be  eliminated  while  working  M^th  sensory 
stimulation.  The  only  course  open  seems  to  be  to  confine  it  within 
as  narrow  limits  as  circumstances  will  permit,  and  to  endeavour  by 
control  experiments  to  differentiate  what  mental  reactions  may  re- 
main from  the  sensory  reactions  under  investigation. 

The  odours  were  at  first  administered  to  the  subject  by  holding  a 
bottle  under  his  nose  and  allowing  him  to  smell  its  contents.  This 
was  the  plan  pursued  by  Lehmann,f  but  it  is  open  to  several  obvious 
objections.  The  disturbance  of  mental  equilibrium  occasioned  by 
such  a  procedure  is  itself  sufficient  to  condemn  it.  Any  sudden  or 
unexpected  movement  of  the  operator  produces  a  mental  reaction 
in  the  subject.  On  the  other  hand,  I  soon  found  that  when  he  an- 
ticipated my  movement  a  reaction  appeared.  When  he  saw  me 
reaching  for  the  odour  bottle,  even  when  I  did  not  apply  the  stimu- 
lus, a  reaction  appeared  which  was  often  very  similar  to  that  accom- 
panying the  sensation  itself.  It  is  evident,  then,  that  the  subject 
should  be  isolated,  and  everything  that  could  attract  his  attention 
as  far  as  possible  removed.  To  attain  this  end  a  screen  was  placed 
between  the  subject  and  the  kymograph,  so  as  to  prevent  him  from 
perceiving  the  recording  apparatus  or  any  of  my  movements,  and  a 
special  apparatus  was  devised  for  administering  the  odour  without 
exciting  or  disturbing  the  subject. 

The  apparatus  used  for  applying  the  odours  is  shown  in  Plate  I. 
By  means  of  an  aspirator,  a,  attached  to  a  hydrant  tap,  air  and  cold 
water  are  mixed  together  and  poured  into  a  large  bottle,  t.  The 
water  is  drawn  off  by  a  siphon.     The  air  is  forced  out  through  a 

*  Kreislauf  des  Blutes  im  mensch.  Gehim.  f  Op.  cit,,  p.  82. 


T.  E.  Shields  21 

small  tube,  5,  which  connects  with  a  coil  of  lead  pipe  immersed  in  a 
warm  bath  of  constant  temperature.  This  gives  us  a  constant  cur- 
rent of  washed  air  of  any  desired  size  at  a  constant  temperature  and 
in  constant  hygrometric  condition.  A  tube,  ^o,  conducts  this  current 
of  air  into  a  metal  pipe,  y,  fastened  to  the  front  of  a  drawer  in  the 
kymograph  table.  A  series  of  thirteen  metal  stopcocks  open  along 
the  upper  surface  of  this  pipe.  In  the  front  of  the  drawer  is  ar- 
ranged a  series  of  thirteen  bottles,  each  containing  a  small  portion  of 
odoriferous  substance.  A  pair  of  small  glass  tubes  perforate  the  stop- 
per of  each  bottle  and  terminate  at  its  lower  surface.  One  of  each 
of  these  pairs  of  tubes  connects  with  a  corresponding  stopcock  on 
the  metal  pipe.  Each  of  the  other  tubes  communicates  with  a  cor- 
responding glass  tube  which  passes  down  through  the  bottom  of  the 
drawer,  bends  over  to  the  screen,  and  runs  up  to  about  the  level  of 
the  subject's  head,  where  it  terminates  after  passing  through  the 
screen.  Thirteen  flexible  tubes  connect  these  glass  tubes  with  thir- 
teen short  metal  tubes  which  are  screwed  into  a  terminal  plate,  the 
odour  plate,  Z',  and  end  on  a  level  with  its  distal  surface.  A  tube, 
14,  which  does  not  make  connection  with  any  odour  bottle,  leads  di- 
rectly from  the  stopcock  on  the  end  of  the  metal  pipe  to  a  four- 
teenth metal  tube  in  the  odour  plate.  This  permits  a  current  of 
odourless  air  to  be  administered  when  desired. 

The  odour  plate  (Z',  Plate  I  and  Fig.  3)  is  a  copper  disk,  eight 
inches  in  diameter,  supported  from  its  centre  on  a  universal  holder, 
which  allows  it  to  be  adjusted  in  any  desired  position.  Through 
this  plate  are  bored  five  series  of  fourteen  holes  each,  arranged  in 
five  concentric  circles.  The  odour  tubes  terminate  in  the  inner  circle 
of  holes.  The  lumen  of  a  short  portion  of  the  terminal  end  of  these 
metal  tubes  is  less  than  half  the  diameter  of  that  of  their  proximal 
end.  Thirteen  of  these  tubes  are  provided  with  electric  valves  con- 
structed so  as  to  work  noiselessly  and  to  leave  the  face  of  the  plate 
as  free  as  possible.  This  prevents  the  subject  from  perceiving  the 
opening  or  closing  of  the  valves,  except  by  his  sense  of  smell,  and 
removes  from  the  face  of  the  plate  all  objects  to  which  odours  might 
cling. 


22    Effect  of  Odours^  Irritant  Vapours^  etc.,  upon  the  Blood  Flow 


Fig.  3  shows  the  construction  of  one  of  these  valves.  A  metal 
disk,  A,  faced  with  rubber  dam  is  placed  in  the  large  end  of  the 
tube.  The  diameter  of  the  disk  is  less  than  the  large  lumen  of  the 
tube  and  greater  than  its  small  lumen.  A  small  wire,  J,  passes  from 
the  centre  of  this  disk  out  through  the  small  lumen  of  the  tube,  and 
a  few  millimetres  from  the  face  of  the  plate  is  fastened  to  a  metal 
rod,  c,  which,  after  running  outward  parallel  with  the  face  of  the 
plate  for  a  short  distance,  bends  back  at  a  right  angle,  passes  through 
a  perforation  in  the  plate,  and  is  adjusted  by  two  nuts  to  one  end  of 
an  armature  lever,  d.  This  armature  lever  runs  outward  parallel 
with  the  plate,  and  terminates  over  an  electro-magnet,  e.  It  is  sup- 
ported on  a  pivot,  h\  situated  a  short  distance  centrally  to  the  mag- 
net.    A  small  spiral  spring,^,  fastened  to  the  odour  plate  is  adjusted 


h  ^MMB 


1\\\<\\\^         ,^^    z' 


^^ 


Fig.  3. — Z,  terminal  plate  (odour  plate) ;  H,  holder ;  A,  metal  disk  for  closing  odour 
tube ;  6,  wire  from  centre  of  disk  A  to  rod  C ;  C,  rod  connecting  wire  of  valve  to  armature ; 
d,  armature  lever;  e,  electro-magnet;  6',  pivot  of  armature  lever;  ff,  spiral  spring  from 
armature  lever  to  terminal  plate ;  A,  insulated  binding  screw. 

to  the  central  arm  of  the  lever  by  a  small  nut  and  bolt,  which  allow 
the  tension  of  the  spring  to  be  regulated  at  pleasure.  One  wire  of 
the  electro-magnet  makes  contact  with  the  plate ;  the  other  passes  to 
an  insulated  binding  screw,  h,  fastened  to  the  plate  beside  the  coil. 
The  tension  of  the  spring  is  so  adjusted  as  to  hold  the  valve  closed 
except  while  a  current  is  passing  through  the  magnet,  and  to  pre- 
vent the  armature  from  touching  the  magnet  at  any  time.  This 
prevents  noise,  and  the  rubber-dam  face  renders  the  valve  itself 
noiseless.  The  movement  of  the  wire  on  the  face  of  the  plate  in 
opening  or  closing  the  valve  is  so  small  that  it  escapes  the  notice  of 
the  subject. 

A  wire  from  one  pole  of  a  battery  makes  contact  with  the  metal 


T.  E.  Shields  23 

pipe  on  the  face  of  the  kymograph  drawer.  Each  of  the  thirteen 
stopcocks  on  the  upper  surface  of  this  pipe  is  provided  with  a  plati- 
num contact,  which,  when  the  stopcock  is  open,  dips  into  a  corre- 
sponding mercury  well  situated  on  the  upper  surface  of  the  drawer 
between  the  stopcock  and  its  odour  bottle.  A  wire  passes  from  each 
of  these  mercury  wells  to  a  corresponding  binding  screw,  thence 
through  the  coil  of  the  electro-magnet  to  the  terminal  plate.  A 
wire  in  contact  with  the  copper  terminal  plate  passes  to  the  magnet 
of  the  signal  pen,  and  thence  back  to  the  other  pole  of  the  battery. 

The  opening  of  any  of  these  thirteen  stopcocks,  therefore,  sends 
a  constant  current  of  air  through  the  corresponding  odour  bottle,  and, 
by  completing  the  electric  current,  opens  the  terminal  end  of  the 
corresponding  odour  tube  near  the  subject's  nose,  and  marks  the  in- 
stant of  stimulation  on  the  paper  of  the  kymograph. 

Opening  the  fourteenth  stopcock  at  the  end  of  the  metal  pipe 
sends  a  current  of  odourless  air  to  one  of  the  odour  tubes  of  the 
odour  plate. 

To  secure  quiet  and  exclude  light  stimulation,  the  subject  was  at 
first  placed  in  a  separate  and  darkened  room.  I  soon  found  that 
movements  of  any  part  of  the  body  might  produce  a  change  in  the 
volume  of  the  inclosed  arm.  It  was  necessary,  therefore,  to  bring 
him  into  a  position  where  I  could  observe  any  movement  he  might 
make.  A  screen  was  placed  so  as  to  prevent  him  from  seeing  me  or 
the  recording  apparatus.  The  room  was  of  course  kept  quiet,  and 
visitors  excluded  except  where  their  presence  is  noted.  All  the 
records  discussed  here  were  taken  by  the  improved  form  of  appa- 
ratus described  wabove. 

Discussion  of  Results. 

To  illustrate  the  character  of  the  records  actually  obtained, 
several  specimens  (reduced  in  size)  of  the  tracings  upon  the  kymo- 
graph are  given  in  Plate  III,  Figs.  1,  2,  3.  Fig.  1  illustrates  the 
vasomotor  reaction  obtained  in  a  certain  instance  by  the  odour  of 
extract  of  heliotrope,  and  Fig.  2  shows  the  effect  of  formic  acid  when 
inhaled  into  the  nose.     The  lowermost  line  gives  the  time  record  in 


24    Effect  of  Odours^  Irritant  Vapours^  etc.^  upon  the  Blood  Floxo 

seconds;  above  this  is  the  pulse  record  taken  by  the  tambour;  and 
above  this  the  volume  curve  of  the  arm  upon  which  the  pulse  move- 
ments are  not  perceptible.  A  fall  of  this  curve  indicates  a  shrinkage 
of  the  arm  due  to  vaso-constriction.  At  the  top  of  the  tracing  the 
respiratory  movements  are  recorded ;  and  above,  the  signal  pen 
marks  the  time  of  application  of  the  sensory  stimulus — i.  e.,  in  these 
cases  heliotrope  and  formic  acid.  Fig.  3  is  a  portion  of  a  tracing 
in  which  the  effect  of  isobutyric  acid  was  studied.  This  tracing 
may.be  taken  for  special  description,  as  it  illustrates  one  of  the  main 
difficulties  met  with  in  interpreting  the  curves.  The  subject's  arm 
was  in  the  cylinder  about  fifteen  minutes  when  this  portion  of  the 
record  was  begun.  Curve  E  gives  the  time  in  seconds.  Ordinates 
are  drawn  at  every  fifth  second.  The  base  line  F  is  drawn  parallel 
to  the  curve  E.  The  pulse  curve,  D,  shows  very  little  change  in 
the  heart  rate.  There  are  nineteen  heart  beats  in  the  first  fifteen 
seconds,  and  about  eighteen  in  each  succeeding  fifteen  seconds.  The 
respiratory  curve,  B,  shows  no  very  great  irregularities.  The  vaso- 
motor curve,  C,  shows  an  increase  of  1'2  cubic  centimetres  in  the 
volume  of  the  arm  during  the  first  twelve  seconds.  Curve  A  indi- 
cates that  the  odour  of  isobutyric  acid  was  turned  on  at  the  tenth 
second,  but  it  is  evident  from  the  respiratory  curve  (phase  of  expira- 
tion) that  it  could  not  have  reached  the  olfactory  meml)rane  much 
before  the  twelfth  second.  At  this  point,  the  arm  ceases  to  increase 
in  volume,  and  three  seconds  later  it  begins  to  decrease.  At  the 
twentieth  second  it  shows  a  diminution  of  1*5  cubic  centimetres. 
The  curve  then  slowly  returns  to  the  base  line,  which  it  almost 
touches  at  the  thirty-eighth  second.  It  indicates  a  second  diminu- 
tion of  one  cubic  centimetre  at  the  forty -fifth  second.  After  this  the 
curve  rises  slowly  and  crosses  the  base  line  at  the  sixtieth  second. 
This  is  followed  at  intervals  of  about  ten  seconds  by  three  positive 
waves  and  one  negative  wave,  not  shown  in  the  figure,  of  somewhat 
less  than  five  cubic  centimetres.  This  curve  would  seem  to  indicate 
that  the  odour  of  isobutyric  acid  produces  a  reflex  stimulation  of  the 
vasoconstrictor  fibres  of  the  arm,  but  I  do  not  think  it  furnishes 
suflicient  evidence  for  such  a  conclusion.     The  curve  in  other  places 


T.  E.  Shields  25 

frequently  shows  just  the  opposite  effect,  although  the  conditions 
remained  the  same.  To  be  at  all  certain  of  the  effect  of  any  par- 
ticular stimulation  we  must,  at  least,  know  the  general  movement 
going  on  for  some  time  before  and  after  the  stimulation.  To  avoid 
the  inconvenient  length  of  the  original  records  needed  for  such  a 
study,  I  have  condensed  their  data  into  plotted  curves,  several  of 
which  (Plates  IV,  Y,  YI,  and  YII)  accompany  this  article.  In  these 
curves  the  distance  between  the  ordinates  marks  intervals  of  ten  sec- 
onds each.  Curve  A,  at  the  bottom  of  the  plates,  gives  the  changes 
in  the  amplitude  of  the  pulse  waves.  The  absolute  value  of  this 
amplitude  might  easily  be  determined  empirically,  but  this  I  have 
not  done.  Nor  can  I  calculate  it  exactly,  since  I  failed  to  keep  a 
record  of  the  magnification  due  to  the  leverage  of  the  writing  appa- 
ratus. But  as  this  leverage  was  not  varied  during  any  of  the  indi- 
vidual records,  its  effect  could  have  no  influence  on  the  changes  which 
occur  during  the  same  record.  The  vertical  distance  between  tbe 
abscissae  represents  about  two-tenths  of  a  cubic  centimetre  in  volume. 
Curve  T>  gives  the  heart  rate.  For  this  curve  the  distance  between 
each  two  abscissae  represents  one  beat  per  minute.  Curve  C  gives  the 
changes  in  the  volume  of  the  arm  in  cubic  centimetres.  The  vertical 
distance  between  the  abscissae  represents  a  change  of  two-tenths  of  a 
cubic  centimetre.  The  pulse  amplitude  and  the  volume  changes  are 
calculated  at  every  fifth  second.  The  heart  rate  is  reckoned  for  every 
ten  or  fifteen  seconds.  The  time  of  stimulation  by  the  various  odours 
is  indicated  in  the  plates.  The  respiratory  curve  was  taken  in  all  the 
original  records,  and  whenever  it  presented  any  marked  irregularities, 
this  fact  is  noted  on  the  plates. 

In  order  to  study  the  effects  of  repetition  and  of  individual  varia- 
tion in  response  to  the  same  odours,  the  experiments  were  arranged 
in  two  series.  The  first  series  of  experiments  were  all  made  on 
the  same  subject ;  the  second  series  were  made  on  twelve  different 
individuals. 

J^irst  /Series. 

Mr.  George  Bill,  who  acted  as  subject  in  the  first  series  of  ex- 
periments, is  a  mechanic,  thirty-three  years  of  age,  in  good  health, 


26     Effect  of  Odours,  Irritcmt  Vapours,  etc.,  upon  the  Blood  Flow 

of  fair  muscular  development,  and  not  particularly  susceptible  to 
odours.  His  arm  was  kept  in  the  cylinder  about  an  hour  daily  from 
the  middle  of  October  to  the  middle  of  January.  He  was  trained  to 
keep  his  mind  as  blank  as  possible.  The  monotony  of  daily  repeti- 
tion soon  removed  the  disturbances  which  in  untrained  subjects 
arise  from  the  novelty  of  the  surroundini^s.  The  odours  of  heliotrope, 
wood  violet,  wintergreen,  musk,  skatol,  and  indol  were  used  daily  ; 
a  few  others  were  used  occasionally. 

Defects  in  the  earlier  forms  of  apparatus  used  render  the  experi- 
ments made  during  October  and  November  unsatisfactory.  Plates 
TV  to  VI,  inclusive,  give  the  results  of  three  experiments  of  this 
series,  which  were  made  during  December  and  January,  when  all  the 
conditions  were  most  favourable,  and  may  serve  as  examples  of  the 
o-eneral  results  obtained  from  this  series. 

One  of  the  most  obvious  features  of  these  curves  is  the  general 
increase  in  the  volume  of  the  arm  which  they  exhibit  during  the 
course  of  the  experiment.  In  one  experiment  there  was  an  increase 
of  39  cubic  centimetres  in  the  volume  of  the  arm  between  the  4:50th 
and  the  2350th  seconds;  in  another,  an  increase  of  30  cubic  centi- 
metres between  the  1st  and  the  1360th  seconds;  a  third  gave  an  in- 
crease of  35  cubic  centimetres  between  the  20th  and  the  1300th 
seconds ;  and  in  a  fourth  the  arm  increased  37  cubic  centimetres  in 
volume  between  the  1st  and  the  1900th  seconds. 

Several  facts  indicate  that  this  increase  in  the  volume  of  the 
arm  is  due  not  to  the  temperature  or  pressure  of  the  water  in  the 
arm  cylinder,  but  to  the  mental  condition  of  the  subject ;  for  in 
other  experiments  on  the  same  subject,  though  the  temperature  and 
pressure  of  the  water  were  the  same  as  in  the  series  just  described, 
no  such  general  increase  in  volume  occurred,  nor  did  it  take  place 
in  experiments  made  on  the  other  subjects.  Second,  the  volume 
of  the  arm  decreased  immediately  when  anything  attracted  the  sub- 
ject's attention.  In  Experiment  Y  (Plate  IV)  the  subject  was  rest- 
ing quietly  with  his  arm  in  the  cylinder  for  ten  or  fifteen  minutes 
before  I  began  to  take  the  record.  During  this  time  the  arm  in- 
creased several  cubic  centimetres  in  volume.     One  hundred  seconds 


T.  E.  Shields  27 

after  the  record  was  begun  Dr.  K.  entered  the  room  quietly,  but  was 
perceived  by  the  subject.  The  volume  of  his  arm  decreased  11"5 
cubic  centimetres  in  the  following  50  seconds.  One  hundred  and 
fifty  seconds  later,  as  Mr.  G.  entered  the  room,  a  further  decrease 
of  4  cubic  centimetres  in  20  seconds  ensued.  After  both  had  left 
the  room  the  arm  immediately  began  to  increase  and  continued  to 
increase  to  the  end  of  the  experiment.  In  Experiment  X,  I  spoke  to 
him  at  the  240th  second.  This  occasioned  a  fall  of  5  cubic  centi- 
metres in  a  few  seconds.  Twice  in  the  course  of  this  experiment  I 
turned  on  the  odour  of  formic  acid  for  a  few  seconds ;  each  time  it 
occasioned  a  sudden  diminution  in  the  volume  of  the  arm. 

The  subject  had  grown  familiar  with  his  surroundings ;  the  chair 
was  very  comfortable,  the  room  quiet ;  there  was  nothing  to  attract 
his  attention,  and  as  a  consequence  his  mind  quieted  down,  and  he 
was  frequently  dozing  toward  the  end  of  the  experiment.  In  Ex- 
periment YII  he  slept  from  about  the  300th  second  to  the  end  of 
the  experiment.  It  was  found,  too,  that  in  these  experiments  the 
heart  rate  became  slower  and  steadier  as  the  arm  increased  in  vol- 
ume— an  indication  that  the  subject  was  gradually  quieting  down  or 
going  to  sleep.  These  facts,  I  think,  show  pretty  clearly  that  this 
general  increase  in  the  volume  of  the  arm  is  due  to  diminished  mental 
activity ;  but,  whatever  may  be  its  cause,  it  must  be  taken  into 
account  in  calculating  the  efiect  of  any  particular  sensory  stimulation. 
To  check  an  upward  movement  of  the  curve  is  practically  the  same 
thing  as  to  cause  a  downward  movement  of  a  curve  that  is  running 
horizontally.  A  horizontal  line  evidently  can  not  be  taken  as  a  base 
line  in  calculating  local  changes.  The  base  line  must  run  in  the 
general  direction  of  the  curve.  It  is  not  an  easy  matter  to  deter- 
mine accurately  what  this  line  should  be  ;  but  in  most  cases  it  may 
be  approximated  and  a  line  obtained  which  will  be  much  nearer  the 
truth  than  a  horizontal  would  be. 

The  curves  also  exhibit  two  species  of  local  variation  which  do 
not  seem  to  be  connected  with  sensory  stimulation.  In  most  of  the 
curves  small  oscillations  occur,  which  suggest  Traube-Hering  waves. 
Besides  these,  larger  and  slower  changes  occur  at  irregular  intervals, 


28    Effect  of  Odours^  Irritant  Yaponrs^  etc.^  upon  the  Blood  Flow 

which  seem  to  be  due  to  variations  in  the  mental  condition  of  the 
subject.  These  changes  are  the  most  annoying  factors  in  the  curves. 
I  have  been  unable  to  eliminate  them  ;  and  it  is  very  difficult,  if  not 
impossible,  to  determine  the  part  they  play  in  the  volume  changes 
which  take  place  during  sensory  stimulation. 

Some  peculiar  features  appear  in  Plate  Y,  which  are  probably 
due  to  the  fact  that  the  subject  was  asleep  during  most  of  the  ex- 
periment. The  arm  increased  rapidly  in  volume  from  the  begin- 
ing  of  the  record  to  the  1300th  second,  and  gradually  decreased  from 
this  to  the  end  of  the  experiment.  The  subject  had  been  resting 
quietly  with  his  arm  in  the  cylinder  for  some  time  before  the  record 
was  begun.  He  seemed  to  be  asleep  about  the  300th  second  ;  at  the 
430tb  second  I  spoke  to  him  and  found  that  such  was  really  the 
case.  He  did  not  wake,  but  his  arm  decreased  3  cubic  centimetres 
in  the  following  20  seconds,  and  then  increased  more  rapidly  than 
before;  75  and  120  seconds  later  two  other  falls  of  about  4  cubic 
centimetres  occurred  which  did  not  seem  to  be  connected  with  any 
external  stimulus.  At  the  1930th  second,  50  seconds  after  a  musk 
stimulation  had  ceased,  there  was  a  fall  of  5*5  cubic  centimetres  in  30 
seconds.  At  the  2250th  second,  during  an  indol  stimulation,  there 
was  a  fall  of  Q'Q  cubic  centimetres  in  35  seconds,  followed  by  an  in- 
crease of  9  cubic  centimetres  in  265  seconds,  when,  35  seconds  after 
the  indol  stimulation  had  ceased,  there  followed  another  fall  of  7*6 
cubic  centimetres  in  30  seconds.  The  odour  of  wintergreen  was  now 
turned  on  for  150  seconds,  during  which  time  the  volume  of  the  arm 
increased  4  cubic  centimetres ;  5  seconds  later  there  was  a  fall  of  5 
cubic  centimetres  in  35  seconds.  During  the  following  400  seconds 
four  or  five  similar  falls  of  less  extent  occurred.  At  the  3150th  second, 
during  askatol  stimulation,  the  subject  woke  with  a  deep  inspiration  ; 
the  heart  rate  changed  from  56  to  80  ;  the  volume  of  the  arm  in- 
creased 20  cubic  centimetres  in  70  seconds,  and  presently  decreased 
almost  as  rapidly.  He  spoke  to  me  at  the  3250th  second,  and  seemed 
asleep  100  seconds  later.  This  sudden  increase  in  the  volume  of  the 
arm  upon  awaking  is  noteworthy,  as  ordinarily  the  reverse  result  is 
obtained,  the  arm  decreasing  in  size  as  the  subject  returns  to  a  con- 


T.  E.  Shields  '  29 

scions  condition.  The  probable  explanation  of  the  unusual  result  in 
this  case  will  be  given  presently  in  speaking  of  the  changes  in  heart 
rate. 

How  are  these  changes  in  the  volume  of  the  arm  to  be  interpreted  ? 
The  curve  throughout  its  entire  extent  exhibits  rhythmic  changes 
which  suggest  Traube-Hering  waves.  Are  the  larger  changes  men- 
tioned above  of  a  similar  nature  ?  There  is  a  certain  periodicity 
about  them,  and,  if  we  except  the  sudden  increase  in  volume  which 
occurred  at  the  3150th  second,  they  resemble  the  small  changes  in  all 
but  extent,  and,  even  in  this  respect,  it  will  be  seen  that  they  gradu- 
ally shade  off  into  each  other.  It  is  possible  that  they  are  caused  by 
variation  in  cerebral  activity.  This  explanation  would  harmonise 
with  Mosso's  observations  on  the  changes  in  cerebral  circulation  dur- 
ing sleep.*  Changes  in  mental  activity  invariably  cause  changes  in 
the  volume  of  the  arm ;  the  play  of  the  sleeper's  imagination  may 
account  for  the  changes  with  which  we  are  here  dealing.  Some  facts 
in  the  curve  itself  point  in  this  direction.  The  fall  at  the  430th  sec- 
ond was  apparently  caused  by  my  speaking  to  the  subject.  The 
large  increase  in  the  volume  of  the  arm  at  the  3150th  second  upon 
awaking  appears  to  be  due  chiefly  to  the  very  great  acceleration  in 
heart  rate,  which  occurred  at  that  moment.  This  was  during  a  skatol 
stimulation,  but  it  will  be  seen  from  the  other  records  that  skatol 
does  not,  itself,  quicken  the  heart  rate.  Did  the  foul  odour  occasion 
an  unpleasant  dream  in  which  some  spasm  of  emotion  caused  the 
sudden  increase  in  heart  rate  and  woke  the  subject  ?  Speculation 
concerning  the  origin  of  these  changes,  however,  will  be  of  little 
value  until  we  have  more  data  at  our  disposal.  The  question  which 
immediately  concerns  us  here  is  whether  or  not,  when  all  due  allow- 
ances are  made  for  changes  produced  by  other  causes,  the  curve  still 
presents  any  evidence  of  sensory  reactions.  We  will  be  in  a  better 
position  to  answer  this  question  after  we  have  made  a  comparative 
study  of  the  other  curves.  The  odour  of  formic  acid  was  administered 
once  for  a  few  seconds  in  Experiment  IX  and  twice  in  Experiments 

*  Mosso.     Kreislauf  des  Blutes,  Leipzig,  1881,  S.  74  fE. 


30    Effect  of  Odours^  Irritant  Vapours^  etc.,  upon  the  Blood  Flow 

YI,  YIII  (Plate  YI),  and  X.  Each  time  it  prevented  full  respira- 
tion, and  caused  a  sudden  and  quite  large  decrease  in  the  volume  of 
the  arm.  The  same  result  was  invariably  obtained  whenever  I  used 
formic  acid.  Lehmann  ^  obtained  similar  results  with  ammonia  and 
bisulphide  of  carbon,  which  he  used  as  typical  unpleasant  odours.  I 
think,  however,  that  the  reactions  in  these  cases  are  due  in  greater 
measure  to  the  irritating  action  of  these  substances  on  the  termina- 
tions of  branches  of  the  trigeminal  nerve  in  the  mucous  membrane  of 
the  nose  than  to  their  odours. 

In  Experiment  YIII,  Plate  YI,  acetic  acid  was  administered  at 
the  1260th  and  again  at  the  lllOth  second.  Each  time  it  produced 
a  diminution  of  9  cubic  centimetres  in  about  50  seconds.  It  was  also 
administered  in  Experiment  YI  at  the  1400th  second,  in  Experiment 
X  at  the  1450tli  second,  and  at  the  end  of  Experiment  XI ;  but  in 
none  of  these  cases  did  it  produce  any  marked  reaction.  The  cause 
of  this  discrepancy  in  results  is  not  apparent. 

Propionic,  butyric,  isobutyric,  and  valeric  acids  were  adminis- 
tered on  several  occasions  without  any  very  decisive  reactions 
appearing. 

In  Experiment  YI  propionic  acid  was  administered  at  the  2225th 
second.  A  fall  of  4  cubic  centimetres  occurred  during  the  66  sec- 
onds of  the  stimulation  ;  but  it  is  not  at  all  certain  that  this  fall  wa& 
due  to  the  acid,  since  similar  falls  occur  throughout  this  curve  with- 
out any  apparent  dependence  on  sensory  stimulation.  In  Experi- 
ment YIII,  Plate  YI,  at  the  2160th  second  the  volume  of  the  arm 
increased  3  cubic  centimetres  during  the  first  40  seconds  of  a  propi- 
onic acid  stimulation,  and  decreased  1-8  cubic  centimetres  during  the 
remaining  20  seconds.  But  this  stimulation  followed  immediately 
upon  a  fall  of  11  cubic  centimetres  produced  by  formic  acid.  The 
curve  usually  rises  in  this  manner  in  such  cases  without  any  sensory 
stimulation.  The  fall  during  the  latter  part  of  the  stimulation  was 
possibly  due  to  the  acid.  Propionic  acid  was  administered  again  at 
the  1870th  second  in  Experiment  X.     There  was  a  rise  here  of  1*5 

*  Op.  cit.,  p.  84 


T.  E.  Sliields  31 

cubic  centimetres  during  the  20  seconds  of  tiie  stimulation  ;  but  this 
rise  is  in  the  general  direction  of  the  curve,  and  presents  no  evidence 
whatever  of  a  sensory  reaction.  In  Experiment  YI  butyric  acid  was 
administered  from  the  lYlOth  to  the  1890th  second,  and  valeric  acid 
from  the  2000th  to  the  2175th  second.  Falls  occurred  in  both  in- 
stances ;  but  from  the  general  movement  of  the  curve  it  would 
appear  that  they  are  rhythmic  contractions,  and  independent  of 
the  stimulations.  At  the  1920th  second  in  Experiment  YIII,  Plate 
YI,  the  curve  was  rising  rapidly  and  continued  to  rise,  apparently 
uninfluenced  by  the  butyric  acid  which  was  turned  on  during  the 
following  50  seconds.  At  the  end  of  the  stimulation  the  curve  took 
a  horizontal  direction,  which  it  kept  during  the  following  130  sec- 
onds. Yaleric  acid  was  administered  during  75  seconds  of  this  time 
without  producing  any  apparent  effect.  Butyric  acid  was  also  ad- 
ministered at  the  1715th  second  in  Experiment  X.  A  fall  of  2  cubic 
centimetres  occurred  during  the  first  30  seconds,  but  the  curve  shows 
that  this  also  may  be  a  rhythmic  contraction.  Isobutyric  acid  was 
used  once  in  each  of  the  Experiments  YI,  YIII,  IX,  X,  and  XI  with- 
out any  apparent  effect. 

Besides  formic  acid  and  the  two  instances  of  acetic  acid  men- 
tioned above,  there  are  three  other  causes  which,  when  present,  usu- 
ally produce  a  marked  diminution  in  the  volume  of  the  arm.  These 
are  a  deep  inspiration,  muscular  movement,  and  mental  activity. 
A  typical  effect  of  a  deep  inspiration  occurred  at  the  1070th  second 
in  Experiment  X.  This  diminution  in  the  volume  of  the  arm  seems 
to  be  due  in  part  to  the  increased  negative  pressure  in  the  pleural 
cavity,  but  I  think  it  probable  that  a  factor  in  the  production  of  this 
reaction  is  the  change  in  the  mental  condition  of  the  subject,  which 
usually  accompanies  an  inspiration  of  this  kind ;  for  on  such  occa- 
sions the  subject  is  usually  drowsy,  and  with  the  deep  inspiration 
the  mind  brightens  temporarily.  It  would  seem  that  there  is  a  con- 
striction of  the  peripheral  arteries,  causing  an  increased  flow  of 
blood  to  the  brain.  When  a  deep  inspiration  occurs  while  the  mind 
is  bright  there  is  seldom  any  very  large  decrease  in  the  volume  of 
the  arm.     It  is  possible  that  when  the  change  takes  place  during  the 


32    Effect  of  Odours,  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

odour  stimulation,  the  stimulation  also  plays  a  part  in  its  production ; 
but  if  so,  the  effect  of  the  odour  can  not  well  be  isolated.  It  is  better, 
therefore,  for  present  purposes,  to  discard  such  reactions.  At  the 
2940th  second  in  Experiment  YI,  I  requested  the  subject  to  move  his 
foot,  which  he  did  during  the  following  fifty  seconds.  The  heart 
beat  immediately  changed  from  72  to  92,  and  after  thirty  seconds 
gradually  returned  to  its  former  rate.  This  sudden  increase  in 
heart  rate  caused  a  transitory  increase  of  6*5  cubic  centimetres  in  the 
volume  of  the  arm,  followed  by  a  decrease  of  13  cul)ic  centimetres 
in  fifty  seconds.  In  this  case  it  is  probable  that  the  effect  was  due 
in  part  to  the  muscular  work  and  in  part  to  increased  mental  ac- 
tivity. Whenever  the  subject  moved  his  foot  unconsciously,  as  he 
sometimes  did,  as  at  the  1670th  second  in  this  experiment,  it  pro- 
duced a  slight  decrease  in  the  volume  of  the  arm,  but  of  course  there 
was  not  nearly  the  same  amount  of  muscular  work  in  these  cases  as 
in  the  instance  referred  to  above. 

The  curves  furnish  numerous  illustrations  of  the  effect  of  mental 
work.  This  factor  always  causes  a  decrease  in  the  volume  of  the 
arm.  A  typical  instance  of  this  occurs  at  the  100th  second  in  Ex- 
periment Y,  Plate  lY.  Sometimes  the  fall  is  preceded  by  a  transi- 
tory rise,  as  at  the  1690th  and  2940th  seconds  in  Experiment  YI ; 
but  in  all  such  cases  the  rise  is  evidently  due  to  a  sudden  accelera- 
tion of  heart  rate.  Besides  these  changes,  which  can  be  definitely 
accounted  for,  the  records  of  this  series  of  experiments  show  a  num- 
ber of  other  variations  in  the  volume  of  the  arm.  The  general 
movement  of  the  curve  has  already  been  discussed.  In  all  the  curves 
small  oscillations  occur  every  few  seconds  which  are  very  much  more 
pronounced  in  some  records  than  in  others,  but  which  remain  pretty 
much  the  same  throughout  the  entire  extent  of  the  same  record. 
These  facts  indicate  that  they  are  influenced  by  the  condition  of  the 
subject  rather  than  by  any  particular  stimulation. 

When  due  allowance  is  made  for  all  these  changes,  do  the  records 
of  this  series  of  experiments  present  any  evidence  of  pure  odour  re- 
actions ? 

White  heliotrope,    wood    violet,    wintergreen,    and    musk   were 


T.  E.  Shields  33 

chosen  as  specimens  of  pleasant  odours  ;  skatol  and  indol  as  unpleas- 
ant odours.  The  subject  enjoyed  the  first  four  very  much  and  dis- 
liked the  latter  two. 

Heliotrope  was  administered  at  the  1365th  second  in  Experiment 
Y,  Plate  lY ;  at  the  220th  and  270th  seconds  in  Experiment  YI ; 
at  the  210th  and  2800th  seconds  in  Experiment  YII,  Plate  Y ;  at 
the  4:5th  second  in  Experiment  YIII,  Plate  YI ;  at  the  850th  and 
1910th  seconds  in  Experiment  XI.  In  none  of  these  instances  is 
there  any  clear  evidence  of  a  reaction.  There  is  not  one  feature 
common  to  these  various  curves.  There  is  scarcely  a  resemblance 
between  any  two  of  them.  The  only  approach  to  a  resemblance 
among  them  is  the  upward  tendency  of  the  curve,  but  this  is  in  the 
general  direction  of  the  curve,  and  evidently  is  not  due  to  the  stimu- 
lation. 

What  has  here  been  said  of  heliotrope  applies  with  equal  force 
to  the  other  five  odours  mentioned.  Yiolet  was  administered  at  the 
430th  second  in  Experiment  YI.  The  volume  of  the  arm  increased 
2  cubic  centimetres  in  the  first  thirty  seconds  and  decreased  4'5 
cubic  centimetres  in  the  following  thirty  seconds  ;  it  then  increased 
to  the  end  of  the  stimulation.  Indol  was  administered  at  the  920th 
second  in  the  same  experiment,  with  very  similar  results.  At  first 
sight  these  look  like  odour  reactions.  But  it  was  found  that  five 
other  similar  falls  occur  in  the  first  1,000  seconds  of  this  experiment, 
at  approximately  equal  intervals  of  time.  The  first  two  falls 
occurred  before  any  odour  was  administered ;  the  third,  fifth, 
and  sixth  in  intervals  between  stimulations.  The  latter  portion  of 
the  curve  presents  a  similar  series  of  falls.  Besides,  if  the  falls  oc- 
curring during  the  violet  and  indol  stimulations  were  odour  reactions, 
we  would  expect  that  they  would  be  repeated  with  some  regularity 
in  numerous  experiments  on  the  same  subject ;  but  such  is  not  the 
case.  It  is  altogether  probable,  therefore,  that  we  are  here  dealing 
not  with  sensory  reactions,  but  with  rhythmic  contractions  of  the 
blood  vessels.  A  comparison  of  the  curves  obtained  by  repeated 
applications  of  any  one  of  these  six  odours  will  make  it  clear  that,  if 
the  stimulation  had  any  effect  on  the  volume  of  the  arm,  it  is  very 


34     Efect  of  Odours^  Irritant  Vapours,  etc,  njpon  the  Blood  Flow 

thoroughly  masked  by  other  movements  of  the  curve.  If  the  odours 
really  produced  any  characteristic  effects  they  would  come  out  in  a 
composite  curve  made  from  a  large  number  of  experiments.  I 
have  not  yet  a  sufficient  number  of  experiments  to  give  any  value  to 
such  a  composite  curve. 

The  experiments  presented  here  are  essentially  similar  to  a  num- 
ber of  other  experiments  made  on  the  same  subject,  all  of  which 
were  conducted  with  great  care;  but  the  results  obtained  do  not 
justify  any  such  conclusions  as  those  which  Lehmann  deduces  from 
his  experiments. 

"  Jeder  lusterregende  Eindruck  erzeugt  eine  Vergrosserung  des 
Yolumens  des  Armes  und  der  Hohe  der  einzelnen  Pulsschliige  nebst 
einer  Vergrosserung  der  Tiefe  des  Atemholens."  ^ 

"  Einfache,  unlusterregende  Sinneseindriicke  rufen,  wenn  sie 
schwach  sind,  sogleich  eine  Yerminderung  des  Armvolumens  und 
der  Hohe  der  einzelnen  Pulsschlage  hervor.  Das  Yolumen  nimmt 
bald  wieder  zu,  trotz  der  Yerkleinerung  der  Pulsschliige,  und  iiber- 
schreitet  gewohnlich  die  Norm,  wenn  die  Pulsschlage  ihre  vorige 
Grosse  erreicht  haben,  die  iibrigens  im  allgemeinen  ebenfalls  iiber- 
schritten  wird.  Bei  stiirkeren,  aber  doch  nicht  schmerzhaften  Ein- 
driicken  treten  diese  Yeranderungen  mehr  hervor  und  werden  zu- 
gleich  unmittelbar  nach  Anfang  der  Reizung  von  einigen  tiefen 
Atembewegungen  begleitet."  f 

"  Einfache  lustbetonte  Sinnesempfindungen  werden  von  einer 
Gefiisserweiterung  begleitet  und  vielleicht  auch  zugleicli  von  einer 
Yergrosserung  des  Urafanges  der  Herzkontraktionen  in  Yerbindung 
mit  einer  Erhohung  der  Innervation  der  willkiirlichen  Muskeln,  je- 
denfalls  der  Atmungsmuskeln.";}; 

An  inspection  of  the  curves  of  this  series  will  satisfy  any  one 
that  none  of  these  statements  is  true  of  them.  Heliotrope  and  wood 
violet  are  certainly  pleasant  odours  and  were  enjoyed  by  the  subject ; 
yet  the  volume  of  the  arm  diminished  quite  as  often  as  it  increased 
during  their  application.    Indol  and  skatol  are  unpleasant  odours,  yet 

*  Op.  cit.,  p.  8-2.  f  Ibid.,  p.  89.  :}:  Jbld. 


T.  E.  Shields  35 

the  volume  of  the  arm  frequently  increased  during  the  first  few 
seconds  of  their  application,  and  then  decreased.  It  is  not  certain, 
however,  that  any  of  these  changes  were  pure  odour  effects.  It  is 
but  proper  to  say  that  the  results  obtained  in  this  series  with  the 
perfected  apparatus  were  all  obtained  from  the  subject  after  he  had 
been  repeatedly  used  in  similar  experiments  involving  the  same  set 
of  odours.  There  were  some  indications  that  the  vasomotor  effects 
in  the  beginning  were  more  pronounced  than  toward  the  end,  when 
the  odours  had  lost  somewhat  of  their  pleasant  or  unpleasant  effects 
and  the  subject  endured  them  in  a  rather  perfunctory  manner,  but 
it  is  not  possible  to  speak  definitely  as  to  this  point,  since  the  earlier 
apparatus  employed  was  subject  to  so  many  errors  that  the  records 
then  obtained  were  not  trustworthy. 

Second  Series. 

The  second  series  of  experiments  was  made  on  twelve  students, 
ranging  from  twenty  to  thirty  years  of  age.  Each  experiment 
lasted  about  an  hour.  The  same  odours  and  acids  were  used  as  in  the 
former  experiments.  There  are  some  features  common  to  all  these 
experiments. 

In  the  first  couple  of  experiments  with  each  subject  the  curve 
exhibited  very  little  of  the  tendency  to  rise  which  constituted  such  a 
prominent  feature  of  the  series  already  described;  but  this  tendency 
became  more  pronounced  in  the  third  and  fourth  experiments. 
Where  the  general  tendency  of  the  curve  is  upward  the  heart  rate 
also  becomes  slower  and  steadier.  This  supports  the  view  advanced 
above,  that  the  gradual  increase  in  the  volume  of  the  arm  and  the 
slowing  of  the  heart  rate  are  due  to  the  diminished  mental  activity, 
and  is  therefore  more  pronounced  when  the  subject  has  become  ac- 
customed to  the  plethysmograph  and  ceases  to  feel  the  mental  excite- 
ment naturally  attendant  upon  a  novel  experience.  The  small 
oscillations  in  the  curves  are,  as  in  the  former  series,  characteristic  of 
the  experiment.  They  are  much  more  pronounced  in  some  experi- 
ments than  in  others,  but  remain  pretty  constant  throughout  the 
whole  extent  of  the  same  experiment. 


36     i^ftct  of  Odours.  L^riUiut  Vapours,  eh\,  upofi  the  Blood  Fhw 

The  reactions  in  all  the  experiments  are  in  the  same  direction, 
but  thev  varv  in  extent  with  the  different  subjects,  with  the  same 
subject  at  different  times,  and  with  the  diff'erent  stimuli. 

Plate  YII  (Experiment  XII)  will  serve  as  an  illustration  of  the 
reactions  obtained  froiu  subjects  who  are  sensitive  to  odours.  This 
was  the  third  experiment  on  Mr.  D.,  who  is  a  student  twenty-two 
years  of  a^e.  of  rather  slight  build,  and  nervous  temperament. 

The  amplitude  of  the  pulse  wave  diminishes  to  about  one  half  at 
the  tirst  odour  stimulation,*  and  does  not  again  return  to  its  original 
size.  The  heart  rate  slows  up  considerably  during  the  experiment. 
The  general  tendency  of  the  volume  curve  is  slightly  upward. 

The  subject  was  resting  quietly  with  his  arm  in  the  cylinder  for 
ten  or  fifteen  minutes  before  the  record  was  begun.  During  this 
time,  and  for  the  first  370  seconds  of  the  record  itself,  the  volume 
of  the  arm  increased  slowly,  without  exhibiting  any  very  marked 
changes.  Heliotrope  was  administered  from  the  3T0th  to  the  725th 
second.  During  the  first  50  seconds  of  this  period  the  volume  of  the 
arm  decreased  19*5  cubic  centimetres.  It  increased  about  1  cubic 
centimetre  during  the  following  50  seconds,  and  li  cubic  centimetres 
during  the  next  125  seconds.  This  was  followed  bv  a  fall  of  4*5 
cubic  centimetres  in  25  seconds,  and  a  rise  of  7*5  cubic  centimetres 
in  100  seconds.  The  prompt  fall  at  the  beginning  of  the  stimulation, 
and  the  fatigue  effect  after  about  100  seconds  are  pretty  good  evi- 
dence that  this  is  an  odour  reaction,  especially  when  it  is  taken  in 
connection  with  the  character  of  the  curve  previous  to  the  stimula- 
tion. This  conclusion  is  confirmed,  I  think,  by  the  fact  that  a 
similar  reaction  was  obtained  every  time  I  used  this  odour  on  Mr.  D. 
Two  other  heliotrope  stimulations  occur  in  this  record  with  results 
very  similar  in  everything  but  extent ;  and  this  difference  is  at  least 
partially  accounted  for  by  the  fact  that  at  the  740th  second  I  moved 
the  terminal  plate  farther  from  the  subject's  nose  so  as  to  diminish 
considerably  the  strength  of  the  stimulation. 

The  fall  of  IS  cubic  centimetres  which  occurred  between  the 
740th  and  the  790th  second  is  a  mental  reaction   caused    by  my 

*  The  original  record  of  part  of  this  stimulation,  reduced  in  size,  is  given  in  Plate  IH,  Fig.  1. 


T.  E.  Shields  37 

speaking  to  the  subject  and  readjusting  the  odour  plate.  When  the 
volume  of  the  arm  had  returned  to  about  its  former  condition  and 
seemed  inclined  to  remain  pretty  steady  I  turned  on  wood  violet.  It 
will  be  seen  that  the  reaction  is  very  similar  to  the  previous  heliotrope 
reaction,  only  less  extensive.  There  is  a  fall  of  8*4  cubic  centimetres 
in  the  first  30  seconds.  It  remains  down  about  25  seconds,  and  in- 
creases 6*5  cubic  centimetres  in  70  seconds,  when  a  second  fall  of 
3*7  cubic  centimetres  occurs.  Wintergreen  was  turned  on  from  the 
1265th  to  the  1440th  second  ;  the  reaction  is  very  similar  to  the  pre- 
vious violet  reaction  in  every  respect  but  the  extent  of  the  second 
fall.  I  had  requested  the  subject  before  the  experiment  began  to 
leave  his  mind  as  blank  as  possible,  and  not  even  to  speculate  about 
the  nature  of  the  odours.  So  great,  however,  was  the  down  sweep 
of  the  curve  that  I  suspected  the  presence  of  a  mental  reaction,  and 
accordingly  at  the  1500th  second  I  turned  on  a  current  of  odourless 
air  strong  enough  to  be  felt  on  his  face.  When  the  experiment  was 
over  I  remarked  to  him  that  he  had  not  obeyed  my  instructions,  but 
had  been  indulging  in  speculations  concerning  the  odours.  He  as- 
sured me  that  such  was  the  case  on  only  one  occasion  for  a  few 
seconds,  when  he  felt  the  air  coming  from  the  tube  but  could  per- 
ceive no  odour.  This  indicates  that  the  reaction  in  the  other  in- 
stances are  connected  in  some  way  with  the  odours.  At  the  1650th 
second  heliotrope  was  again  administered.  There  was  a  prompt  fall 
of  10  cubic  centimetres  in  35  seconds,  followed  by  two  quite  large 
falls  during  the  course  of  the  stimulation.  After  an  interval  of  150 
seconds,  during  which  time  there  was  very  little  change  in  the  volume 
of  the  arm,  musk  was  turned  on.  It  occasioned  a  prompt  fall  of  8 
cubic  centimetres  in  20  seconds.  The  two  secondary  falls  were  very 
slight.  Skatol  was  turned  on  from  the  2640th  to  the  2740th  second 
without  any  apparent  effect.  Heliotrope  was  administered  for  the 
third  time  at  the  2760th  second.  The  reaction  is  essentially  similar 
to  the  two  former  instances.  I  spoke  to  him  at  the  3060th  second. 
An  acquaintance  entered  at  the  3150th  second.  When  the  subject 
had  quieted  down  I  turned  on  formic  acid  for  35  seconds.  This 
caused  a  fall  of  18  cubic  centimetres  in  50  seconds. 


38    Effect  of  Odours,  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

This  record,  as  has  ah'eadj  been  said,  was  chosen  as  a  specimen 
of  very  pronounced  odour  reactions,  but  each  of  the  twelve  subjects 
on  whom  this  series  of  experiments  was  made  gave  unmistakable 
evidence  of  reactions  to  odours  and  irritant  vapours.  The  reactions 
were  always  in  the  same  direction,  although  seldom  as  pronounced 
as  in  the  case  of  Mr.  D.  In  the  mental  reactions  obtained  in  this 
series  it  was  found  that  the  volume  of  the  arm  decreased  very  mark- 
edly notwithstanding  a  simultaneous  quickening  of  the  heart  rate. 
This  is  characteristic  of  the  mental  reactions  in  all  my  experiments, 
A  second  striking  peculiarity  of  the  mental  reactions  is  their  long 
continuance.  The  effect  of  odours  or  irritant  vapours  passed  off  in 
three  or  four  minutes  at  most,  whereas  mental  work  frequently  kept 
the  heart  beating  at  a  high  rate  and  kept  the  volume  of  the  arm  low 
for  many  times  that  period. 

The  relation  existing  between  the  effects  of  sensory  stimulation 
and  of  mental  work  will  be  discussed  in  a  future  paper. 

Stjmmaky. 

The  most  important  outcome  of  this  investigation  has  been  the 
completion  of  various  improvements  in  the  construction  and  use  of 
the  plethysmograph,  by  means  of  which  numerous  errors  attending 
the  use  of  the  instrument  have  been  eliminated. 

The  results  of  the  work  show  that  all  olfactory  sensations,  so  far 
as  they  produce  any  effect  through  the  vasomotor  system,  tend  to 
diminish  the  volume  of  the  arm,  and  therefore  presumably  cause  a 
congestion  of  the  brain.  Whenever  the  stimulation  occasions  an  in- 
crease in  the  volume  of  the  arm,  as  sometimes  happens,  it  seems  to 
be  due  to  acceleration  of  the  heart  rate,  which,  of  course,  tends  also 
to  increase  the  supply  of  blood  to  the  brain.  The  effect  of  odours 
varies  in  extent  with  differeiit  individuals,  and  with  the  same  indi- 
vidual at  different  times.  It  was  most  marked  in  subjects  sensitive 
to  odours.  Irritant  vapours,  such  as  formic  acid,  have  a  marked  effect 
in  the  same  direction — that  is,  they  cause  a  strong  diminution  in  the 
volume  of  the  arm.  The  experiments  give  no  support  to  the  view 
that  pleasant  sensations  are  accompanied  by  a  diminution  of  the 


T.  E.  Shields  39 

blood  supply  to  the  brain  and  unpleasant  sensations  by  the  reverse 
effect.  In  all  my  experiments  mental  work  caused  a  marked  and 
prolonged  diminution  in  the  volume  of  the  arm.  This  vasomotor 
effect  was  sometimes  preceded  by  a  transitory  increase  in  the  volume 
of  the  arm  caused  by  acceleration  of  heart  rate. 

Acknowledgment. 

I  wish  to  return  my  sincere  thanks  to  Prof.  Howell,  at  whose 
suggestion  this  work  was  undertaken,  and  whose  kind  supervision 
and  advice  was  a  constant  help  and  encouragement  at  every  step  of 
its  progress.  I  am  further  indebted  to  him  for  his  generosity  in  pro- 
viding a  subject  for  the  first  series  of  experiments.  I  am  also  in- 
debted to  Prof.  E.  A,  Pace,  of  the  Catholic  University,  for  many 
valuable  suggestions  on  the  psychological  aspects  of  the  problem,  and 
to  the  Rev.  C.  A.  Pamm  for  suggestions  in  the  constructions  of  the 
apparatus,  and  for  the  three  accompanying  drawings. 

1  must  also  take  this  opportunity  of  thanking  the  young  gentlemen 
of  St.  Mary's  Seminary,  who  generously  placed  their  time  at  my  dis- 
posal in  acting  as  subjects  for  the  second  series  of  experiments.  My 
thanks  are  due  in  a  special  manner  to  Messrs.  Riedel  and  Beavan, 
who  acted  as  subjects  in  a  number  of  experiments  and  who  assisted 
me  in  the  laborious  task  of  tabulating  the  results  and  plotting  the 
curves. 

June  1,  1895. 

Explanation  of  Plates. 

Plate  I. — General  Aerangement  of  Apparatus. 

A,  B,  support  for  test  tube  and  siphon  ;  C,  D,  D',  clamps  for  same ;  E,  clamp  for  spiral; 
F,  F',  wires  from  spiral  to  rubber  ring;  H,  I,  tube  connecting  siphon  with  arm  cylinder;  J, 
four-way;  1,  2,  3,  4,  stopcocks  on  same;  K,  piston  tube;  S,  metal  cap  for  same;  M,  M', 
stay  rods  to  upright ;  N,  piston  rod ;  0,  0',  rods  connecting  metal  cap  with  washer ;  P,  Q, 
supply  jars ;  Q,  milled  nut  for  adjusting  level  of  piston ;  Q',  milled  nut  for  adjusting  indi- 
cator ;  R,  rubber  ring  carrying  test  tube ;  S,  spiral  suspending  test  tube ;  T,  test  tube ;  TJ, 
upright ;  W,  washer  over  milled  nut  on  piston  rod  ;  X,  tambour ;  T,  T-way  in  tube  con- 
necting piston  tube  with  tambour ;  A,  B,  stopcocks  on  same ;  w,  Z,  three-way  stopcocks 
on  supply  tubes ;  A,  aspirator ;  t,  bottle  for  washing  air ;  U,  bath  for  warming  air ;  ?/,  air 
tube  on  face  of  kymograph  drawer;  z\  terminal  plate;  e,  electro-magnet;  d,  armature;  Ji, 
binding  screw ;  d,  ring  suspending  arm  cylinder. 


40     Efect  of  Odours,  Irritant  Vapours,  etc.,  upon  the  Blood  Flow 

Plate  II. — Arrangement  of  Cylinder  and  Method  of  holding  the  Arm  Rigid. 

A,  arm  ring ;  B,  wristlet  band  ;  C,  D,  rubber  rings  for  making  arm  holder  rigid  to  arm 
cylinder ;  G,  H,  faces  of  arm  ring ;  M,  M',  rods  making  arm  ring  rigid  to  wristlet ;  R,  ring 
cemented  into  rubber  sleeve ;  S,  rubber  sleeve ;  e,  I,  m,  orifices  in  arm  cylinder ;  h,  ther- 
mometer ;  t,  stopcock  to  let  air  escape  from  arm  cylinder ;  Y,  metal  band  for  supporting 
cylinder ;  K,  supply  tube ;  rf,  ring  from  which  arm  cylinder  is  suspended. 

Plate  III. — Specimens  of  Tracing  (reduced  one  half  in  size)  taken  upon  the 

Kymograph. 

1.  Heliotrope  stimulation  (subject,  Mr.  D.).  2.  Formic-acid  stimulation  (very  light  current 
of  vapour).  3.  Isobutyric-acid  stimulation  (subject,  George  Bill):  A,  signal — isobutyric  acid 
turned  on  from  10th  to  end  of  record  ;  B,  respiratory  curve — expiratory  phase  from  10th  to 
12th  second  shows  that  the  stimulation  could  not  have  reached  olfactory  membrane  before  the 
12th  second;  C,  vasomotor  curve;  shows  increase  of  12  cubic  centimetres  in  volume  of 
arm  between  the  1st  and  12th  second,  a  decrease  of  15  cubic  centimetres  at  the  20th  sec- 
ond, a  return  to  base  line  at  38th  second  and  a  second  decrease  of  1  cubic  centimetre  at 
45th  second,  and  a  return  to  base  line  at  60th  second;  D,  heart  rate.  It  shows  19  heart 
beats  in  first  15  seconds,  and  about  18  in  each  succeeding  15  seconds ;  E,  time  in  seconds ; 
F,  base  line  ;  ordinates  are  drawn  at  every  fifth  second. 

Explanation  of  Plotted  Curves.     Plates  IV,  V,  YI,  and  VII. 

A,  changes  in  amplitude  of  pulse  wave  ;  vertical  distance  between  abscissae  0"2  cubic  cen- 
timetre. D,  heart  rate ;  vertical  distance  between  each  two  abscissae  represents  one  beat 
per  minute.  C,  changes  in  volume  of  arm ;  vertical  distance  between  each  two  abscissae 
represents  0-2  cubic  centimetre.  The  distance  between  the  ordinates  makes  intervals  of  10 
seconds  each.  The  pulse  amplitude  and  volume  changes  are  calculated  at  every  fifth  sec- 
ond. The  heart  rate  is  reckoned  for  every  10  or  15  seconds.  The  respiratory  curve  was 
taken  in  all  the  original  records.  Whenever  it  presents  any  marked  irregularities  this  fact 
is  noted  on  the  plates.    Time  of  stimulation  by  the  various  odours  is  indicated  on  the  plates. 

Plate  IV. — December  3d  (subject,  Mr.  George  Bill).  Resting  with  arm  in  cylinder  15 
minutes  before  record  began.  Volume  of  arm  increasing  slowly.  Heart  rate,  60.  100th 
second,  Dr.  K.  entered.  Volume  of  arm  decreased  115  cubic  centimetres  in  60  seconds. 
250th  second  Mr.  G.  entered.  Volume  of  arm  decreased  4  cubic  centimetres  in  20  seconds. 
Heart  rate  changed  to  68,  64,  71,  64,  72,  68.  490th  second.  Dr.  K.  and  Mr.  G.  leave  room. 
Heart  rate,  60.  Volume  of  arm  increases  rapidly  to  700th  second,  and  more  slowly  to  end 
of  record.  Subject  dozing  toward  end  of  experiment.  Heart  rate  gradually  sinks  to  52  at 
end  of  experiment.  Total  increase  of  volume  of  arm  between  450th  second  and  end  of 
experiment,  39  cubic  centimetres,  due  to  diminished  mental  activity. 

Plate  V. — December  12th  (subject,  Mr.  George  Bill).  Resting  quietly  with  arm  in 
cylinder  for  some  time  before  record  began.  Asleep  from  300th  second  to  end  of  experi- 
ment. Heart  rate  60  during  most  of  the  experiment.  No  odour  reaction.  Volume  of  arm 
increases  30  cubic  centimetres  between  1st  and  1360th  seconds.  Small  rhythmic  contrac- 
tions every  10  or  15  seconds.  Spoke  to  him  at  the  430th  second,  which  occasioned  a  fall 
of  3  cubic  centimetres  in  20  seconds.  530th  second,  fall  of  4  cubic  centimetres.  650th 
second,  fall  of  4  cubic  centimetres.  1930th  second,  fall  of  5*5  cubic  centimetres  in  30  sec- 
onds. 2250th  second,  fall  of  6'6  cubic  centimetres  in  35  seconds.  2515th  second,  fall  of 
7*6  cubic  centimetres  in  30  seconds.  2710th  second,  fall  of  5  cubic  centimetres  in  35  sec- 
onds. Four  or  five  similar  falls  of  less  extent  occur  during  the  following  400  seconds. 
None  of  these  falls  seem  to  be  due  to  odour  stimulation.     They  are  probably  rhythmic  con- 


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T.  E.  Shields  41 

tractions.  3150th  second,  subject  woke  with  deep  inspiration.  Heart  rate  changed  from 
56  to  80,  probably  due  to  a  spasm  of  emotion  caused  by  unpleasant  dream.  Volume  of  arm 
increased  20  cubic  centimetres  in  '70  seconds,  apparently  due  to  quickened  heart  rate.  3250th 
second,  subject  spoke  and  seemed  asleep  100  seconds  later.  Arm  returned  to  its  former 
volume  and  heart  rate  to  60.  Amplitude  of  pulse  wave  diminishes  from  beginning  to  end 
of  experiment.     3250th  second,  about  one  third  its  initial  amplitude. 

Plate  VI. — December  14th  (subject,  Mr.  George  Bill).  Volimie  of  arm  increases  12 
cubic  centimetres  during  first  1100  seconds.  1260th  second,  acetic-acid  stimulation,  dimi- 
nution 9  cubic  centimetres  in  volume  of  arm  in  30  seconds.  1410th  second,  acetic  acid,  with 
similar  result.  1580th  second,  formic-acid  stimulation  for  15  seconds,  occasioning  a  fall  of 
13  cubic  centimetres  in  80  seconds.  2100th  second,  formic-acid  stimulation  for  30  sec- 
onds, with  a  fall  of  11  cubic  centimetres  in  60  seconds.  Odour  stimulations  apparently 
without  effect  throughout  the  curve.  Amplitude  of  pulse  wave  diminishes  gradually  through- 
out the  experiment. 

Plate  VII. — January  31st  (subject,  Mr.  D).  Subject  resting  quietly  with  arm  in  cyl- 
inder 15  minutes  before  record  began,  during  which  time  and  for  the  first  3Y0  seconds  of 
the  record  itself  volume  of  arm  increased  slowly  without  any  marked  changes.  Heart  rate 
gradually  slows  during  experiment.  Volume  of  arm  exhibits  a  slight  upward  tendency 
during  most  of  the  experiment.  Amplitude  of  pulse  wave  diminished  to  about  half  at  the 
first  odour  stimulation,  and  does  not  return  to  its  original  size.  3'70th  second  to  725th, 
heliotrope  stimulation.  Volume  of  arm  diminishes  19'5  cubic  centimetres  in  first  50  sec- 
onds, increases  1  cubic  centimetre  during  the  following  50  seconds,  and  14  cubic  centi- 
metres during  the  next  125  seconds.  595th  second,  fall  of  4-5  cubic  centimetres  in  25  sec- 
onds. 740th  second,  spoke  to  subject;  fall  of  18  cubic  centimetres.  1020th  second, 
wood-violet  stimulation,  fall  of  84  cubic  centimetres  in  first  30  seconds  ;  second  fall,  3-7 
cubic  centimetres  at  1145th  second.  1270th  second,  wintergreen  stimulation,  fall  of  8'5 
cubic  centimetres  in  30  seconds;  a  second  slight  fall  at  1370th  second.  1500th  second, 
current  of  air;  subject  speculates  as  to  its  nature;  fall  of  4*5  cubic  centimetres  in  a  few  sec- 
onds. 1650th  second,  heliotrope  stimulation;  fall  of  10  cubic  centimetres  in  35  seconds,  fol- 
lowed by  two  quite  large  falls  in  course  of  the  stimulation.  2350th  second,  musk  stimula- 
tion; fall  of  8  cubic  centimetres  in  20  seconds,  followed  by  two  slight  secondary  falls. 
2640th  and  2740th  seconds,  skatol  stimulation,  no  apparent  effect.  2760th  second,  helio- 
trope ;  fall  of  10  cubic  centimetres  in  30  seconds.  2870th  second,  fall  of  2"5  cubic  centi- 
metres in  15  seconds.  2985th  second,  fall  of  6  cubic  centimetres  in  30  seconds.  3060th 
second,  subject  spoke;  fall  of  11  cubic  centimetres  in  90  seconds.  3150th  second,  S.  en- 
tered room;  fall  of  2'5  cubic  centimetres  in  30  seconds.  3270th  second,  fall  of  3  cubic 
centimetres  without  obvious  cause.  3450th  second,  formic-acid  stimulation  for  30  seconds ; 
faU  of  18  cubic  centimetres  in  50  seconds. 


BIOGRAPHY. 
Thomas  Edward  Shields  was  born  on  the  9th  of  May,  in  the 
jear  1862,  at  Mendota,  one  of  the  suburbs  of  St.  Paul.  Minn,  In 
1882  he  entered  the  sophomore  class  of  St.  Francis  College,  Mil- 
waukee, and  ^-emained  there  until  1885,  completing  its  classical  cur- 
riculum. In  September,  1885,  he  began  his  philosophical  studies  in 
the  theological  seminary  of  St.  Thomas  Aquinas  at  St.  Paul.     Here 


42     Effect  of  Odours^  Irritant  Vapours^  etc.,  vpon  the  Blood  Flov) 

he  passed  six  years :  two  years  in  the  study  of  mental  philosophy, 
ethics,  and  the  physical  sciences,  and  four  years  in  the  study  of  the- 
ology— dogmatic  and  moral — and  the  accompanying  branches  of 
Holy  Scripture,  Church  history,  and  canon  law.  He  was  ordained 
priest  on  March  l-i,  1891,  and  in  the  following  June  was  assigned 
as  curate  to  the  Cathedral  of  St.  Paul.  After  fourteen  months  in 
the  active  ministry  there  he  came  to  Baltimore  (in  September,  1892), 
received  the  degree  of  Master  of  Arts  from  St.  Mary's  University, 
and  began  his  studies  in  the  Biological  Department  of  the  Johns 
Hopkins  University  in  October  of  the  same  year. 


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